The T-4 and AX-15 are not interchangeable. The AX-5 will bolt in place of the T-4, and it is a bit stronger, but it's not really up to the task of controlling the torque of a 4.3L. If you want a 4.3L, you'll have to swap both engine and tranny at the same time (and don't forget to match the t-case input shaft spline count too). Why not go with a Chevy 3.1/3.4L? It's a much easier (and cheaper) swap and it'll bolt up to you T-4. Later, if/when the T-4 dies, you can then swap in an AX-5. Any MJ/XJ with the 2.8L engine will have almost all the necessary brackets, motor mounts, exhaust parts, etc that you'll need. And if you find a 3.1/3.4L still in the late80s/early90s Camaro/Firebird, then you'll have all the parts needed to swap in the fuel injection. You can try car-part.com to search junkyards to see what parts are going for. A pull-your-own-part junkyard will be even cheaper.
Jeep on!
--Pete
