'89 XJ with tranny trouble

AW4 tranny is slipping, so it's time to replace. I know that '87-90 is a direct replacement, but any suggestions on things that will go in/upgrade? I've done a bit of searching and it looks like a '91-'96 will go in with a little work, but I'm not sure what's involved. Did the usual newbie search, but couldn't track down anything conclusive (could just be i didn't know what to search for though :dunce: )

http://www.naxja.org/forum/showthread.php?t=68552
...this was my previous post which gave me the info.

I"m open to moving into other transmissions other than the AW4 if there are other ideas out there as well.

I believe that the newer trannys/guage clusters have electronic speedometers, versus the older cable ones. The pilot(?) bearing on manual trannys are different too between the years.

I wouldn't give up on the tranny just yet. What gear is it slipping in?