Didn't look super hard then, did you? :hmm:
Start here http://www.rollaclub.com/board/index.php?s...18428&st=15 which is one of the later threads on this topic, and have a read through some of the members ride sections.
TA22 wont bolt in, as the spring platforms are for coils. Leaf platforms will have to be added. Stud pattern will also change.
If you want to keep the 20 pattern, you may have to look at Mazda diffs, as they predominately have the same stud pattern. (4 x 110) Investigated this for about 2.5 minutes and then wrecked my other rally car, and thus my 25 has a t series diff with 4.77 LSD from the grunter. (4 x 114.3 pattern).
I don't like you luck at being able to bolt a mazda diff in, as I think you would probably have to change the spring mounts in some way.
Cheers
R