The AW4 is much more common, but there are three other Jeep options in select years of Jeep Wranglers and Jeep Grand Cherokees. The AW4 has a different offset for the flexplate, so make sure you match the flexplate to the donor transmission. The difference in flexplate is very subtle, so many people have successfully installed an AW4 with torqueflite flexplate or vice versa to discover severe converter damage a short time later.
Also you need the matching starter.[qoute]
All 4.0 XJ's had the AW4. Its a very well designed transmission, fairly strong, although much harder to rebuild yourself than the old TF998 or TF727. They are computer controlled and benefit from an overdrive. They are best matched with 3.55 rear axle ratio, although the more common 3.07 is still a good match. All automatic XJ's were 3.55's. An AW4 is slightly longer, approximately an inch, and may require a new rear driveshaft. The front driveshaft may still work because there is very little travel needed and about an inch of adjustment available in the slip joint. It will bolt directly to your original Eagle transfer case.
[/quote]It's about 3.5" longer. I have both here in my carport
The AW4 can be shifted manually gear by gear with an aftermarket computer control. Its expensive and isn't as user friendly as a traditionally installed automatic transmission. That is the only reasonable way to install one without installing the '91 to '95 fuel injection system at the same time because the XJ AW4 computer control is tied directly to the Multiport Fuel Injection computer. Realistically an AW4 is best installed by purchasing a whole XJ parts car and swapping in the entire drivetrain.
It is possible to run the AW4 without the EFI system, but you have to add the sensors and computer controller, so you miteaswell do the conversion to EFI (you'll want the economy anyways)
I highly recommend converting to the NP242 transfer case at the same time, especially if you need to make a custom driveshaft. Look for a 4.0 '91 to '95 Jeep Cherokee parts car with "Selec-trac" in contrast to "Command-trac."
You can run the '87 to '90 trans and tcase together (they are 21 spline and '91 up is 23 spline) and still use the '91 to '95 EFI system. Just make sure you get the harness from a car with auto trans and get the harness/controller for the trans (under the pass side dash)
If you don't want to do the expensive and tedious fuel injection conversion, you should look for a TF727. They are quite common in Jeep Wagoneers. The TF727 is nearly a direct bolt on upgrade. It is about a quarter inch longer than the 998, but your slip joints can compensate for that difference easily. It is a true truck transmission and is the strongest option available.
That would be '80 - '83 Wagoneer or Cherokee, or '84 to '91 Grand Wagoneer or '80 to '88 Jtruck. I have an AW4 in my carport with a NP208 from an FSJ adapted to it. I have another from a '91 XJ I parted with NP231. My '88 MJ has an AW4/NV242 I installed and I have another that is 2wd AW4 that is going into my '82 Spirit with EFI. I have the old 998 on the ground from my Eagle and a 727 I just installed (awaiting a NP228 or 229 so I can finish that job. Wish I'd stuck the old one in for now with the snow that's happening)
I also have a Dodge NP208 (mirror image to the Jeep one) and T18A/NP208 in my '82 Honcho that will be swapped for an AX-15 and the NP208 that's bolted to the AW4 in my carport. Anyone need any pics?