I am guessing that you most likely a 46RH (727 shaped pan) transmission and it should have lockup. That doesn't leave you a lot of choices, I believe 94-95 might be about it---Maybe '96. I think the 93 and earlier are non lockup trans, But don't quote me on that.

I can't remember if it was '96 or '97 that they went to the 46RE transmissions, and those won't work for you.