trans : do you have an auto/want an auto? youll need to change it. the bellhousing pattern is different between the 2.3 and the 5.0/3.8 - an AOD(or C4 and C5) from a 5.0 or 3.8 car would fit
5spd - from what ive seen, you could swap the bellhousing for a 5.0/3.8 bell and use a late 80s probe pilot bearing, but id want to run a 5.0/3.8 T5 instead...1st and 2nd are too tall for the 5.0. the 5.0 T5 has closer gears, too.
rear : no, you dont need to change it...the key word is NEED here...the open 7.5" diff should be okay for a while as long as it isnt already worn badly, but you may atleast want to swap in a traclok diff to stop from doing those peg-leg burnouts

if you want more strength than the 7.5" diff, you can swap in an 8.8" rear
-james