No specialty parts required to do this change.
The stock '57 bushing is fine. Chevy used the same pilot bushing in nearly everything they ever made.
As to what disc to get, you need to know what diameter you need first, as there are several sizes to choose from. All the T5's use the same spline count except the Camaro V8 version, which you don't have. Most likely, a V6 S10 or V6 Camaro will have the right size to use.
First, look inside the tail end of the tranny and see if its still there. It may have been removed allready. If not, you will need to remove the tailhousing to get it off. A heavy duty snap ring pliers is needed to get these off. The little "pin" type pliers won't get it done. An S10 shop manual will have the info you need to go through the T5.
Remember, If you choose not to remove that snapring, then you need to make absolutely sure that the driveshaft won't bottom out on it.
