TR6060 Rebuild

It should require a special tool to remove the 5th/6th driven gear. I'm going to tell you from experience removing mine from the t56 in my 04 GTO, buy the dam tool to remove it and do it correctly! Chip the gear and it's an expensive fubared paperweight.
Some places have a do it all at once "kit" that has all the normal wear items. Be sure you know what it came out of as depending on what vehicle it can and most likely have specific parts to the application. (synchro clutches for instance)
Start here.
www.tickperformance.com