Should've asked on here first. Someone near you could tell you if it's a good place or not. I swapped my 998 for a 727, but the slower takeoff is annoying me, so I'll probably go to an AW4 sooner than later.
The lack of overdrive runs me insane. I do all these distance trips and even a .85 ratio would be a significant advantage. In 3rd gear the cruise speed feels like 22MPH. If I wanted to pull an AW4 and bolt it to my 258, what would have it? Some random 4L Cherokee?
Your gear ratio is probably too low for small tires/no overdrive (mine was too when I put the 3.31 in the Spirit)
AW4 from XJ or MJ (or rare early '93 ZJ) with 4.0L. It's computer controlled and your tcase isn't a direct bolt up. You need either the (other Jeep) tcase that's on the AW4 or a '91 to '95 23 spline AW4 and 1" spacer ring (I got mine from
http://Partsmike.com about 10 years ago when it was going for @ $100)
You also need the flexplate from the 4.0L (if you plan to go EFI, '91 up are HO and different from earlier ones) as well as the starter and the underhood wiring harness along with the computer and the harness to the transmission controller behind the underdash speaker panel on the passenger's side. Grab the top end of the motor (head upgrade with aluminum cover) and all teh sensors too.
Note that '87 to '90 are .70 overdrive and '91 up are .75 (all HO's) The "best" harness for an EFI swap is '91 to '95 (if you find a '96 with the trans computer under the dash still, then it's alright. Newer ones are all one computer OBDII and require extra sensors, etc)
MAKE SURE YOU GET ALL THE BOLTS!!!!!! I use plastic waterbottles with felt pen markings as to where they come from on this setup.
If you run the "other" tcase, you will need the rear driveshaft for sure and mod the length to fit the Eagle. Not sure on the front yet, but avoid the "tincan" style.
Not all yet, but enough to get started.
REMOVE THE CPS on the bellhousing before dropping the trans! They are fragile and have been known to catch and bend the flexplate as they are breaking!