How many bolt holes were there in your trans?

 

There are a few things GM changed throught the years with the 4l80e of course 99 and up would be the best but there is nothing wrong with the 97 and ups as well.
1994 and got new Force motor Solenoids as well as new spacer plate, and accumulator housings.
There was a bigger change with the Center gear box Planetary pinion gears and carriers. Both were built a bit longer and stronger. but you can upgrade any of the older models to the newer design.
Also the 1999 got wider manual 2nd band, which is also intercahngable with earlier versions.