I remember staring at a pile of parts, sweat dripping into my eyes, wondering if I’d just bought a very expensive paperweight. The question burning in my brain was a simple one, but the answer felt buried under layers of industry jargon: are 4 7 and 5 9 gas trsns same bolt pattern?
I’d been told they were interchangeable, but my gut screamed otherwise. This whole thing started because I wanted to swap out an older, finicky carb for something a bit more reliable on my project truck. I ended up down a rabbit hole of adapter plates, spacers, and conflicting forum advice.
It’s a common enough question, and one that can cost you time and money if you get it wrong.
Let’s cut to the chase: sometimes yes, sometimes no. It’s not a straightforward ‘always’ or ‘never’ situation, which is exactly what makes it so maddening when you’re knee-deep in greasy parts. This isn’t some abstract theory; it’s about getting your engine to actually run without sputtering out or, worse, leaking fuel everywhere.
The Basics: What Are We Even Talking About?
When folks ask if 4.7 and 5.9 liter gas engines share the same transmission bolt pattern, they’re usually talking about a specific generation of Chrysler/Dodge/Jeep engines. Think the Magnum V8s. The 4.7L is often found in lighter-duty trucks and SUVs like the Dodge Dakota, Durango, and some Grand Cherokees. The 5.9L, on the other hand, is the legendary ‘360’ small-block V8, a staple in Ram trucks, Jeeps, and muscle cars for decades. They look similar enough under the hood, and they’re both V8s, so it’s natural to assume their ancillaries, like the transmission, would be a perfect match.
The transmission bolt pattern, often called the bellhousing pattern, is the arrangement of bolts that connects the engine’s crankshaft (via the flexplate or flywheel) to the transmission. Different engine families, and even different versions within the same family, can have distinct bellhousing patterns. This is important because the transmission needs to mate perfectly to the engine’s rear main seal housing. If the pattern doesn’t line up, the transmission simply won’t bolt on. It’s not just about the number of bolts; it’s about the diameter of the bolt circle and the precise location of each hole.
I learned this the hard way with a different project, trying to put a newer Ford transmission behind an older Ford engine. Everyone on the forums said ‘just get the adapter plate!’ Well, the adapter plate worked, but it pushed the transmission back an inch, messing up my driveshaft length and costing me another headache. Sometimes, ‘close enough’ is just a recipe for more problems down the line. The goal here is to avoid that domino effect of complications.
So, why the confusion? It often comes down to generational changes and specific applications. Chrysler engineers sometimes made subtle tweaks to bolt patterns even within the same engine family to differentiate certain transmissions or to accommodate packaging changes. It’s rarely a malicious act; it’s usually about design evolution or a specific engineering requirement for a particular vehicle or transmission type. For instance, a transmission designed for a heavier-duty application might have a slightly different bolt pattern than one meant for a car, even if the engines are closely related.
The Real Deal: Are They Actually the Same?
Here’s the blunt truth: for the most part, and specifically when talking about the common configurations most people encounter, the 4.7L Magnum V8 and the 5.9L Magnum V8 (often referred to as the 360) generally use transmissions with the same bolt pattern. This is primarily true for the transmissions that were factory-mated to these engines in the popular Dodge Ram trucks and Jeep Grand Cherokees from the late 90s through the mid-2000s. We’re talking about transmissions like the 45RFE/545RFE (which is basically the same transmission) and the older 46RH/47RH/48RE automatics, and their manual counterparts like the NV3500 or NV4500. These transmissions were designed to bolt up to both the 4.7L and the 5.9L engines of that era.
This interchangeability is a big reason why you’ll find people swapping 5.9L engines into lighter trucks originally equipped with 4.7Ls, or vice-versa, and expecting their transmission to bolt right up. And often, it does. The bellhousing pattern is largely identical between these two Magnum V8s when paired with their common automatic and manual transmissions. This similarity simplifies many engine swap projects and makes finding replacement transmissions less of a headache. You can usually take a transmission from a 5.9L and bolt it onto a 4.7L, and vice-versa, without needing any special adapters, assuming you’re dealing with compatible transmission types for each engine. (See Also: Are All Honda Atv Bolt Patterns The Same )
However, and this is where the ‘sometimes’ comes in, there can be exceptions or nuances. Older versions of the 5.9L (like the ones from the early to mid-90s, often referred to as the LA series engines before the Magnum redesign) might have slightly different bolt patterns or bolt sizes, particularly when mated to older transmissions like the A518 or A727. While still a Chrysler bolt pattern, the precise location and diameter of the bolt holes could differ. Modern interpretations of the 4.7L or 5.9L in later vehicle generations might also have subtle variations if they were paired with entirely different transmission families. Always double-check the specific transmission model and the year range of the engine you’re dealing with.
When ‘same’ Doesn’t Mean Identical: Potential Pitfalls
While the bolt patterns are largely shared, that doesn’t mean you can just grab any transmission from a 4.7L and expect it to work perfectly behind a 5.9L (or vice versa) without a second thought. The bellhousing pattern is just one piece of the puzzle. You also need to consider the torque converter (for automatics) or clutch/flywheel setup (for manuals). The torque converter on a 5.9L engine is typically larger and heavier-duty than what you’d find on a 4.7L, because the 5.9L generally produces more torque. While they might physically bolt to the flywheel/flexplate, the balance might be different, and the torque converter’s stall speed and cooling capacity might not be ideal for the other engine.
I remember a buddy who swapped a 5.9L into a Jeep that had a 4.7L. He used his existing transmission and flexplate. The bolts lined up, and it started. Great, right? Wrong. The torque converter was mismatched. The engine felt sluggish, almost like it was slipping, and the transmission fluid got way hotter than it should have. He ended up blowing out a clutch pack within six months. He learned that day that while the bolt pattern might be the same, the supporting cast of components matters just as much. It’s like having the right actors for a play; the script (bolt pattern) is one thing, but the performance (drivability and longevity) depends on everyone playing their part correctly.
Another common pitfall is mixing manual transmissions. While the NV4500 was used behind both engines, there were different input shaft lengths and spline counts depending on the original application and year. So, even if the bolt pattern on the bellhousing is the same, you might find your driveshaft is suddenly too short or too long, or your clutch disc doesn’t engage properly. It’s easy to get complacent when the main connection seems correct, but all these smaller details can derail your project.
Common Transmission and Engine Pairings to Watch Out For
To give you a clearer picture, here’s a quick look at some common pairings and what to generally expect regarding bolt patterns. This is not exhaustive, and always verify for your specific application.
| Engine | Common Transmissions | Bolt Pattern Similarity | Verdict/Notes |
|---|---|---|---|
| 4.7L Magnum V8 (approx. 1999-2007) | 45RFE, 545RFE, NV3500, NV4500 | Generally Same as 5.9L Magnum | High compatibility for these specific transmissions. |
| 5.9L Magnum V8 (approx. 1993-2003) | 46RH, 47RH, 48RE, NV3500, NV4500 | Generally Same as 4.7L Magnum | The Magnum 5.9L shares the pattern with the 4.7L. |
| Older 5.9L “LA” Series V8 (pre-1993) | A727, A518, A618 | Slightly Different / Older Pattern | May require adapter or specific transmission. Less common swap target for modern builds. |
What to Look for: Practical Checks
When you’re faced with two engines and two transmissions, or when buying parts for a swap, don’t just trust a forum post or a general statement. Get your hands dirty. The best way to confirm if a transmission will bolt up to an engine is to physically compare the bellhousing of the transmission to the rear of the engine block. Look at the bolt holes. Count them. Measure the diameter of the bolt circle – the imaginary circle that passes through the center of all the bolt holes. You can do this with a flexible tape measure or even a piece of string and a ruler.
Ideally, you want to see the transmission bellhousing sitting flush against the engine’s rear seal housing (or adapter plate, if one is used). Are all the bolt holes lining up perfectly? Is there any interference or gap? Sometimes, even if the bolt pattern is the same, the shape of the bellhousing itself might differ slightly, interfering with oil pans, exhaust manifolds, or starter motor mounts. You might need to check the physical dimensions and shape of the bellhousing to make sure it clears all other engine components.
Another practical tip is to check the transmission’s dipstick tube location. On automatics, the dipstick tube often mounts to the side of the bellhousing. If you’re swapping a transmission between different engine families, the location of this mounting hole might be different, or the tube itself might interfere with the engine block or exhaust. It’s a small detail, but these little things can turn a simple swap into a frustrating puzzle. I once spent two hours trying to figure out why my exhaust was hitting my transmission line – turns out the dipstick tube mount was in a totally different spot on the donor transmission.
If you can’t physically compare, the next best thing is to look for the transmission model number and the engine’s specific engine code. Then, do some digging on manufacturer service manuals or reputable parts supplier databases. Sites like Allpar.com are goldmines for Chrysler-specific information. They often detail specific transmission-to-engine compatibility for various model years. Don’t rely on anecdotal evidence from random internet users; try to find data that’s as close to official as possible. (See Also: Are Ak Bolts Interchangeable )
Common Mistakes and How to Avoid Them
The biggest mistake people make is assuming that because the engines are in the same family (like Chrysler Magnum V8s) and the bolt patterns look similar, everything will be a direct bolt-on. This leads to buying the wrong transmission, ordering unnecessary adapter plates, or ending up with a project that’s more complex than anticipated. The ‘good enough’ bolt pattern isn’t always good enough when it comes to torque converters, flexplates, or even the physical dimensions of the bellhousing.
Another common error is not considering the transmission’s electronics. While older transmissions (like the RH series automatics) are mostly mechanical, the later RFE series transmissions (45RFE, 545RFE, 65RFE, 68RFE) are electronically controlled. If you’re swapping a 545RFE from a 5.9L to a 4.7L, you need to make sure your engine’s computer (ECU/PCM) can communicate with and control that specific transmission. Sometimes, this requires a different ECU, a transmission controller module, or a custom tune. Just bolting it up won’t make it shift gears.
I’ve seen people try to force a transmission onto an engine, thinking a little persuasion with a rubber mallet or a bit of grinding will solve the problem. Don’t do it. If it doesn’t seat perfectly and smoothly, there’s a reason. Forcing it can damage the transmission input shaft, the engine’s rear main seal, or the flexplate/flywheel. It’s a sign that something is misaligned. Patience and careful inspection are key. Always make sure you have the correct flexplate or flywheel for your engine and transmission combination. The diameter, bolt holes for the torque converter, and balance weight can all differ.
Here’s a contrarian take: everyone talks about the bolt pattern, but honestly, the supporting drivetrain components often cause more headaches. People focus so much on getting the transmission to bolt to the engine that they forget about driveshaft length, U-joint angles, axle ratios, and even the cooling system for the transmission. A perfectly bolted-on transmission that overheats because it’s not getting enough cooler flow or is paired with the wrong gear ratio will fail just as surely as one that doesn’t bolt up correctly. Prioritize the whole system, not just the connection point.
Real-World Use Cases and Practical Tips
One of the most common real-world scenarios where this question comes up is during engine swaps in popular Dodge Ram trucks. If you have a 1500 series truck with a 4.7L and decide to upgrade to a more powerful 5.9L Magnum V8, you’ll likely be looking at keeping your existing transmission if it’s a suitable automatic like a 45RFE or 545RFE. The good news is, in most cases, this is a straightforward swap. The transmission from the 4.7L will bolt directly onto the 5.9L Magnum, and you’ll retain your existing shifter, linkages, and ECU control (assuming the ECU is compatible with both engine and transmission configurations for that model year range).
Similarly, if you’re taking a 5.9L out of a heavier-duty truck and putting it into a Jeep Grand Cherokee that originally had a 4.7L, you can often reuse the Jeep’s transmission. This simplifies the swap significantly. You’ll just need to make sure you have the correct flexplate for the 5.9L engine and that it’s balanced correctly.
For manual transmissions, the NV4500 is a popular choice for both engines. If you’re swapping an NV4500 that came behind a 5.9L into a truck with a 4.7L, the bellhousing pattern should align. However, you’ll need to make sure the clutch and flywheel are compatible with the 5.9L, and that the input shaft length and spline count of the NV4500 are correct for your specific truck’s transfer case and crossmember setup.
Here are a few practical tips to make your swap smoother:
- Verify Everything: Before buying anything or starting the wrenching, lay the transmission and engine side-by-side if possible. Take photos of the bolt patterns. Compare them closely.
- Check Transmission Model Numbers: Don’t just assume it’s a ’46RH’. Look for the specific tag or cast numbers on the transmission case. Research that exact model number.
- Use the Correct Flexplate/Flywheel: This is important. The flexplate (for automatics) or flywheel (for manuals) is the interface. Make sure it’s designed for your engine and that its balance matches the engine’s crankshaft. A mismatch here can cause severe vibrations and premature component failure.
- Consider Driveshaft Length: When swapping transmissions, especially between different chassis or engine sizes, the length of your driveshaft might change. Measure carefully before and after, and be prepared to get it modified or replaced.
- Plan for Cooling: Automatic transmissions generate a lot of heat. Make sure your transmission cooler is adequate for the new engine’s power output and the transmission’s intended use. Often, an external cooler is a good investment.
People Also Ask:
Can I Put a 5.9 Transmission on a 4.7?
In most common applications for Dodge and Jeep vehicles from the late 1990s to mid-2000s, yes, a transmission designed for a 5.9L Magnum V8 will bolt directly onto a 4.7L Magnum V8. This applies to popular automatic transmissions like the 45RFE/545RFE and manual transmissions like the NV4500. The bellhousing bolt patterns are generally interchangeable for these engine families and transmission types. (See Also: Are All Bolt Patterns The Same )
Will a 46rh Bolt to a 4.7?
No, generally a 46RH transmission will not directly bolt to a 4.7L Magnum V8. The 46RH is typically found behind the older 5.9L (360) LA-series engines or early Magnum 5.9L engines. While both are Chrysler V8s, the bolt pattern on the 4.7L Magnum and the 46RH transmission are different, and you would likely need an adapter plate, which can introduce other complications.
What Transmission Bolt Pattern Does a 5.9 Magnum Have?
The 5.9L Magnum V8 engine (typically from the mid-1990s onward) generally uses the Chrysler Magnum bolt pattern. This pattern is compatible with transmissions like the 46RH, 47RH, 48RE, 45RFE, 545RFE, NV3500, and NV4500, provided they are from compatible model years and applications. This pattern is also shared with the 4.7L Magnum V8.
What Transmission Can I Swap Into My 4.7?
For a 4.7L Magnum V8, you can typically swap in transmissions that were originally mated to it, such as the 45RFE, 545RFE, or the manual NV3500 and NV4500. You can also often use transmissions that were mated to the 5.9L Magnum V8, like the 46RH, 47RH, or 48RE, due to the shared bolt pattern, but you must make sure compatibility with your engine’s electronics and supporting components like the torque converter or flywheel.
Wrapping Up the Bolt Pattern Question
So, to circle back to that initial question: are 4 7 and 5 9 gas trsns same bolt pattern? The most common answer for the Magnum V8 era is a resounding ‘yes, for the most part.’ This is a lifesaver for DIYers tackling engine swaps or repairs. But as we’ve dug into, ‘most part’ is the operative phrase. You absolutely cannot get complacent. The bolt pattern is just the first hurdle, and overlooking the details of torque converters, flexplates, bellhousing clearance, and electronic compatibility can turn a simple job into a costly nightmare.
My advice? Treat every swap like a detective case. Gather all the evidence: engine year, transmission model, vehicle application. Cross-reference with reliable sources, and if at all possible, get your hands on the actual parts to compare. Don’t be afraid to ask detailed questions and verify answers. The time spent doing your homework upfront will save you hours of frustration and dollars spent on incorrect parts and rework down the line. A correctly matched transmission not only bolts up but also performs reliably and efficiently.
Final Thoughts
Ultimately, the question of whether 4.7 and 5.9 gas transmissions share the same bolt pattern boils down to a ‘usually, but check first’ situation, especially if you’re dealing with the popular Magnum V8 engines. This compatibility is a huge advantage for many builds, but it’s not a free pass. Always confirm the specific transmission and engine years you’re working with, and don’t forget to consider the supporting components like flexplates, torque converters, and electronic controls.
Getting this right means your engine will run smoothly and reliably. Getting it wrong means headaches, wasted money, and a project stalled in your driveway. So, before you grab that wrench, do your due diligence. A little extra effort now makes sure your hard work pays off with a functional, powerful setup.
Have you ever run into an unexpected bolt pattern issue on a seemingly similar engine? What was your fix?
