How can I tell the difference between the 4 cycl and a v8 t5?

Am I going to have to change my cross member or anything else when switching to t5? Car is 88 was originally 4cycl 5sp its been swaped to 87 5.0 auto.

 

Here's the TTC pages with the specs for all the different T-5s by part number:

http://www.ttcautomotive.com/English/products/T-5.asp

Also includes a PDF service manual for T-5 Transmissions.

FYI, they warn against mixing trans lubes (Dex-II is spec'd).