spideys85gt

I have a 98 v6 mustang and it has a T-5 in it and it's in need of a rebuild. I have a spare 86 T-5 that I wanted to use to rebuild and put in the 98 so I wasn't without a car for more than the time to swap the trannys. After looking into the rebuild kits there's 2 different kinds of T-5's. I was just wondering if anyone knows for sure if I would be able use the 86 T-5 in the 98, and if the gear ratio's were the only differences.