1. Tranny can be anything- 727, 42rh or 46rh. Computer and harness will be designed for 46rh if 4x4, probably 42rh is 2x4.
2. Luckily dodge kept the motor mount ears cast into the block all the way thru 2000 on the 318 and 2003 on the 5.9. Just need the brackets which you should already have on your LA
3. Gotta swap the whole wiring and computer- can't use the TBI stuff. This, exhaust and fuel lines in the toughest part of the swap cause you're dealing with 39 psi now instead of 14.5.
4. OBD II startted in 96. 92-95 parts trucks are your friend- 94-95 computers will run and drive but have an extra circuit which will affect drivability- I'm working on which one it is

Lastly, keep the serpentine drive off the 91!. It was a one year only, 5.2 only, deal and desirable b/c it will bolt to a LA