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Sometimes the factories that make a certain brand of vehicle never quite put the combination of parts together the way we would like them to be. I mean, there really should have been a 12 cylinder Cat diesel in that CJ5, don't ya think? Well, maybe not, but for all the folks who are swapping V8s, Granny-Trannies like NV4500s, multiple transfer cases, etc, into a vehicle that did not roll off the factory assembly line with those cool parts in place really just needs to look into the aftermarket for support in the quest for the perfect blend of form and function.

Jeeps are more 'swapped into' than any other vehicle. Blessed with a pretty big engine compartment, it is nearly a constitutional right to be able to swap a Chevy 350 into a Jeep's engine bay. Beyond that, you may want to retain the stock Jeep tranny or transfer case. To get this to bolt up to a Chevy engine (or whatever) may require swapping out input or output shafts in gearsets, matching bolt patterns, clutch parts, etc. The possibilties are dizzying.

Enter the king of the hill, the 800 pound gorilla in the aftermarket pool of making stuff fit where it was not intended to - Advance Adapters. Chances are that, unless you are doing something really 'niche' like putting a Nissan diesel into a Suzuki or whatever, Advance Adapters has ya covered.

In my case, I needed a medium duty 5 speed manual tranny behind my Ford 302 HO motor. I wanted overdrive for highway use, I did not want a 4 speed granny-tranny like an NP435 or T-18 even though it would have been way cheaper and easier. Also, for a street driven rig, I hate rowing those old dump truck transmissions. The Ford trannies that ran behind the Mustang like the T-5 are not taken seriously for off road stress and the bigger and more expensive Clark 5 speeds are not really used much either...if you can find one. Also, I wanted a common output spline count and bolt pattern on the back of the tranny and nothing is more common than round, 6 bolt 23 spline. That is what is used on the 6 cyl CJs that used a Dana 300 t-case, the 6 cyl YJs and TJs that used the NP231 cases (there are 21 spline input t-cases, but they ran behind the 4 cyl motors in YJs and possibly TJs).

I did not give an NV4500 too much thought. Run in heavy duty applications and featuring a granny 1st gear AND an OD 5th gear, the NV4500 is pretty much unbreakable in any Jeep. It is also real big, long, requires an adapter, and is expensive to buy. Still, it is worth considering, as a NV4500 with a single transfer case is a versatile option for a dual duty Jeep.

I looked at picking up an AX15 Jeep tranny. Used behind 6 cyl's beginning in 1988 to 1999 in Jeeps of different kinds, the AX15 is a decent tranny and will stand up to mild V8s. It has a 1st gear of 3.83 and an overdrive of .79.

Another option was the NV3550 (pictured below). Nearly indentical to the AX15 in length, weight, etc, it is rated slightly higher in input torque rating (300 ft/lbs, but that is at a pretty high GVWR) and it was used in various configurations (as an NV3500 with integral bell housing) in Chevy applications behind V8s and in Dodge Dakotas besides Jeep Tjs from 2000 to 2004. As a plus, the NV3550 has a 4.0-1 first gear.

nv3550

Not cheap to buy, but still readily available in new and used form, I went for the NV3550. I had the feeling it was considered to be stronger than the AX15 from folks who should know. I found a used one at a local Jeep shop and proceeded to bring it home. The next call was to Advance Adapters (AA). I had already done my homework and I knew they offered kit number 712544. It used a stock Ford bell housing from an F150 with a small block V8 or 300 CI 6 that used a hydraulic clutch. 1987-1988 seem to be the key years, but I have read but could not confirm that the year range is slightly wider than that. The adapter plate matches the bell housing pattern to the NV3550. This is becoming a very popular swap into classic Broncos who want to ditch the 3 speed tranny or 4 speed tranny.

AA Kit #712544 plus other goodies.

I also needed a new flywheel, clutch disc, pressure plate, T/O bearing, pilot bushing, and other assorted Ford parts like the clutch fork, slave cylinder, etc.

Here is the Ford bell housing you will need. Notice the bosses for the slave bracket (red arrows).

The flywheel I sourced from NAPA. It was a part for a 1988 F150, 4 speed, 50 OZ imbalance. The new clutch parts came from AA and I splurged for a Centerforce pressure plate. The list of part numbers is at the bottom of the article. I hit the Pick and Pull for the clutch fork,slave bracket, and bell housing.

You can see the back of the 302 all ready for more parts. I began with the starter shim plate and added the new flywheel from NAPA. Although the holes in the back of the crank look symmetrical, they are not and the flywheel will only bolt up one way. I used medium locktite on the bolts and torqued to spec. As a side note, the indexing placed the cast in 'lump' on the flywheel 180* opposite to the balancer on the front of the crank.

The bronze pilot bushing provided by AA needs to be soaked in oil overnight. After that, I tapped it in place using a small block of wood and hammer. Do not damage the ID of the pilot bushing. It is a close fit on the nose of the tranny. I had an old clutch disc alignment tool in the drawer that had a ten spline count but needed a few wraps of electrical tape to get the nose of the tool to match the ID of the pilot bushing. Or you can buy one that fits to begin with. After that the clutch pressure plate was bolted up and torqued gently and evenly till it set flush on the flywheel. As you are tightening things every once and awhile check to see if the alignment tool will slip in and out freely. If not, you may have the clutch disc slightly off center. I don't have pics of the pressure plate installed. Rats! I must have gotten all excited and forgot.

Once that was done, I turned to the adapter and tranny. You need to grind a bit off the tranny case to allow for two bolt heads to pass through the adapter plate into the bell housing. Do this a bit at a time and check, grind, check, etc. You need to be able to have the bolt pass though at 90* to the tranny adapter or it will not thread into the B/H correctly. You can see the red area in the pic where you need to grind. I used an angle grinder with a flap wheel. The last pic below shows the adapter being bolted to the tranny with the supplied bolts. However, before that happened, I took the adapter plate and went to work on the bell housing.

The NV3550 has a bulge in the face of the input of the tranny case that needs to be allowed for in the bell housing. To see where this needs to be cut or drilled for, I placed the adapter plate so it indexed into the center of the bell housing and loosely screwed in the 4 bolts that hold it all together. I took a marker and drew the circle onto the B/H (bell housing). Now the actual hole in the adapter is larger than the tranny requires by a bit, so I used a 1" bi-metal holesaw and drilled the bell slightly smaller than needed, then I enlarged the hole with a drill motor and round metal bit till it fit juuuuust so. Be certain that the B/Hl sits very flush on the face of the adapter. Mine was rocking very slightly side to side till I saw there is a cast in webbing on the nose of the tranny bulge that was just hitting the B/H. A quick hit with the drill bit on the B/H and that was that. If this was not a flush fit and you tightened it down to the B/H, it would probably crack the aluminum B/H. Then I bolted the adapter to the tranny (as shown above) and test fit the B/H to it all. Good to go!

It was a simple matter of putting the tranny in place after installing the B/H to the back of the motor (and placing the throw out bearing ((clutch release bearing, actually)) and clutch fork in of course). I slid the tranny in place and it bolted up to the B/H just like factory. Voila! Jeep, meet Ford. Ford, Jeep.

I still need to sort out the issue of whether or not the stock YJ clutch master cylinder will drive the slave well enough to achieve full throw at the clutch fork. I will see, but I may have to adapt a Ford master to the Jeep or? Not sure yet. When I get rest of it sorted out I will add it to this article and let you know!

Parts list from Advance Adapters:

Kit # 712544 NV3550 to Ford V8 Adapter

1 711544 Adapter Plate

1 716122 .750 Pilot Bushing

9 720030 Transmission bolts S.H.C.S 10mm x 1.25 x 30mm

4 724317 S.H.C.S 7/16"-14 x 1/4" Bolts

1 383735 11" x 1-1/8" 10 spline clutch disc