My friends wife was involved in an accident that banged up their poor little 2wd 4 banger XJ. The beam is toast so he's tossing around the idea of doing a 4wd swap. I'm not real familiar with the 4wd swap process with the AX-15. I believe his is a 94. My question is what needs done with the transmission? Does he need to swap out the output shaft or get an AX-15 from a 4wd? Any help would be appreciated. I've searched for like half an hour and can't find anything quite like my question.
You have the AX-5, not the AX-15 (AX-4 if you have the four-speed.)
You can probably fit the AX-15 behind the 4-150, but you'll need an adapter plate. As I recall, the 4-150 uses the GM "Metric V6" pattern (common to the V6-60 and later 4-151,) while the 6-242 uses the AMC "I6/V8" pattern (later I6, Gen-II/III V8.) I do now know offhand if the bellhousings will swap between the AX-4/5 and AX-15, but I do believe the input shafts are the same.
2WD/4WD? The 2WD mainshaft is longer than the 4WD - by several inches. I have been told that the BA-10 shaft may simply be cut down (it's splined along its full length,) but I don't know about the 2WD AX-15. The 4WD mainshaft is shorter to accommodate the length of the transfer case within the driveline.
In general, converting any transmission 2WD/4WD requires removal of the mainshaft (manual) or output shaft (automatic) and replacing it with the correct version, in addition to securing and installing the correct output housing.
Since you have the 4-150; and I do believe it uses the GM "Metric V6" pattern, this opens up a new field of donors for you - the S10/S15 series! You can just grab the transmission and transfer case out of one of those (they don't use the AX-4/5, I think they generally use the T4/5 behind the 4-121/4-151 engine, and possibly behind the V6-171/183. However, this is an acceptable gearbox for behind four-cylinders and mild sixes...) and you'll probably net the NP231C transfer case, which has a wider drive chain than the NP231J (1.25" vice 1.00") and is therefore somewhat stronger.
Just a thought... I'd Google the idea of the bellhousing pattern on the 4-150 being the "Metric V6" pattern - but if it is, that opens up a new field of driveline donors for you!