1990 cherokee transmission transplant

I am thinking about putting an auto into my 1990 cherokee....
how diffacult would it be to put a 97 auto transmission into a 90 standard cherokee?
Any thoughts before I begin this annoying task?
And please spare me your manual is better stuff... i know it is, but i am much lazier than you think and my wife really wants to be able to drive it every once in a while... so its worth it to me..

I have access to a 97 transmission for 40 bucks... just needs new solenoids

The swap has been covered many times, so searching should probably turn up a bunch of info. The AW4 auto transmission is electronically controlled, so you'd need to have the trans computer and wiring to go with it. Shifter and cable, swap throttle position sensor, shifter xfer case linkage is longer, etc. There are lots of miscellaneous parts, so its really helpful if you have a donor vehicle to grab parts from.

The big problem you'll run into is that the 97 transmission will not work with a 1990 trans computer as the rear output speed sensor is different. The usual fix is to pull the tailcone and swap over the rotor and sensor from a pre 1997 model. If you have the 1997 trans computer you need to splice it into the existing Throttle Position Sensor instead of using the dual output TPS sensor that's normally used for the trans computer (the TPS signals for the Renix TCU ran opposite of the later years).

Cheapest cost for a replacement set of solenoids is $160 (see http://www.naxja.org/forum/showthread.php?t=996259). On the plus side, the spline counts on the output to the xfer case should be the same.

Not saying it can't be done, but it's certainly not a straightforward as it might sound. Trust me, I've got a 1999 auto in my 89 MJ and found some of the gotchas the hard way.

(oh and yeah I wish I had stayed with the manual, but it destroyed itself and I had the AW4 sitting in the garage)