My recent experiences with using multiple different year cases together seems to be that some parts are the same and some parts don't work with others.
I know for a fact that on the AWD transmission if you want to use a 1g bell housing with 2g internals, you have to make sure to swap out the 1g's shift shaft for the 2g one. This is because the shift nub sticks out further on the 1g shaft than the 2g one. This will create binding with the shift rails. Using all/mostly 2g internals, I used a 1g bell housing, center section & bearing plate. The end case had to be a 2g one to clear the 2g's larger diameter 5th gear hub/slider.
Look at my thread here for problems i've had doing this. Shift Shaft Pin Alternative?
All my experience is with the AWD trans. I cannot guarantee how any of my information may pertain to FWD.