AX-15 to AW4 swap in 91 MJ??

SO...what all would I have to do to swap out the AX-15 in my 91 MJ to an AW4? For clarity, I have a 1996 AX-15 installed using the CJ-5 pilot bushing. Will later model tranny's work? Need to know about wiring the AW4 computer what years to use for compatibility, ect. thanks -J

You'll need a TCU for sure, might need the dual output (6 wire) TPS (I forget if that's a Renix thing only or not, I suspect it is...), may need some additional wiring to the brake pedal switch. If you want it to be OEM-perfect, you'll need an ECU as well and will need more wiring harness modifications. You'll need a new NSS - the one on the AX15 is much simpler obviously. You may need a new VSS, lawsoncl noted in one thread that the number of pulses per revolution is different on the old and new AW4s and such - but I think you can probably bolt on your existing one (anyone know for sure?) You might need a new transmission crossmember, I'm not sure. You will need different front/rear driveshafts - the length of the rear driveshaft will depend on whether or not you have 4wd in the MJ (if you don't, you should be doing that swap at the same time because you'll already be halfway there in terms of complexity!) Luckily you won't need to screw around with different speedo cables since 91 was the first year with electronic odometer/speedo signaling.

That's about all I can think of right now, I'm probably missing something or other.

oh...so I will have to change out the main ECU? that is probably a deal
breaker. I thought the trans computer was stand-alone.

They're sorta stand-alone - going from auto to manual, the ECU will get angry if you disconnect the TCU. I believe you can go manual to auto without it, but it won't be "perfect" as in exactly like an OEM installed automatic tranny setup. As long as it gets the signals from the NSS (get this with the tranny, that way you don't pay for it separately at the junkyard! Just leave it bolted on and they probably won't charge you separately for it), possibly the brake pedal, and the TPS, I'm pretty sure it'll "just work". Could be wrong on this.

Also, a new ECU will only cost you 20-40 dollars at any you-pull-it, just make sure it's from the same year as your MJ, I'm pretty sure a 91 automatic XJ one should work fine. I'd view the driveshafts as more of a dealbreaker personally, they are harder to track down as MJs are not common in junkyards... at least around here.