I've also had a report from the field that an NV4500 was adapted to the AMC242. Goes by MistWolf - but I haven't seen him around lately (time for a trip to the Grand Canyon - he always had such good ideas...) and he did have to, er, "massage" the tunnel sheetmetal to get it to fit.
The AX-15 is a direct replacement - the earlier "internal" slave can use the Peugeot clutch kit (the only thing different is the bearing) so you don't have to change hydraulics. Later AX-15's will require a hydraulics change, but you'll be going from an "internal" slave to an "external" slave, actuating the throwout bearing with a fork. You may also have to change the pilot bushing - the very early AX-15 uses the same size pilot as the BA-10 (the 1990 I had went right in,) but the later pilot is larger.
There's a good thread on the subject here as well -
http://www.naxja.org/forum/showthread.php?t=70388. Several of us have done the swap, and we detail the issues you might run into doing it yourself.
The transmission is a direct swap - but the outputs are different, so you'll really need to score the transmission and transfer case, or get the input set from a 23-spline (late) transfer case and overhaul your old one. 1990-1995 should go right in - if you get the input from a 1996 or later, I'd suggest you grab the entire input gearset, since they changed the cut of the gears. You can use the same driveshafts, tho. Also, the crossmember will have to move back.
I've not been able to track down other donors for the AX-15 yet - it's got a removable bellhousing, so it's possible to "piece the job together." You can also buy conversion kits, if you've got the scratch - check Novak Adapters and Advance Adapters as starting points. If you find a 2WD AX-15, it
can be converted to 4WD - but you'll need a 4WD mainshaft and transfer case adapter housing to do it. Might as well replace all the bearings and seals while you're about it.
Aisin gearboxes are also used in a lot of Toytas - and I think the NV3550 was found in some late-model Dodge Dakota trucks as well. The NV3550 uses the same bellhousing as the "external" AX-15, so that's a possible as well (I don't think there were any "internal" NV3550s, so you'll need an "external" bellhousing. There's a sleeve around the input for the T/O bearing to ride on - and the "hydraulic bearing assembly" won't fit.)
I've just wrung out my brains on the subject, and gotten everything loose. If I come up with anything else, I'll let you know.
Oh - expect the threadserts in the rear crossmember mounting holes to be stripped and/or rusted. If they're good, they're threaded 3/8"-16. If they're shot, you can cut access holes in the frame rail (two small ones are better than one large one,) and use a nut and washer.
