Re: Tranny Swap
The only overdrive automatics that would fit your engine without adapters are the AW4 from the XJs and early '93 ZJs or the 42re/A500 from the newer ZJ 4.0s.
All Dodge transmissions have a different bolt pattern for the engine. Both Jeep overdrive automatics require computers for shifting, and are longer than the 999 you have now. Neither are readily adaptable to your Jeep unless you swapped in the wiring and EFI from a newer Jeep, which aint easy. Hope this helps, good luck!