If you are refering to the tailshaft housing (aka extension housing). Yes older t5 housing will mate up with later model case. HOWEVER. I believe it was in mid 92's and older that they started using the reverse brake synchro. If you get an extension housing for one that does not use a reverse brake synchro the housing is not the same.
If you see the one on the right is the inside of the tailshaft housing for a reverse brake t5 and the one on the left is the non reverse brake. the raised edge is to stop the holder from spinning allowing the synchro to slow the countershaft. You can use a newer tailshaft housing on an older t5 but not vice versa. NOW, if you have a non reverse brake t5 the extension housing can be modified to look like the reverse brake one and in that case would be able to be used no problem, but that is if you are comfortable doing that kind of modification. Ive been in and out of these t5's alot, hope that answers your question.