They are full bearing transmissions, utilizing (if simular to a t56) tapered roller bearing so there will be clearances to measure. I guess I don't think of it when it comes to this stuff since I have micrometers and everything I need to service dam near anything I own so the comment about specialized tools is true to an extent. The 6060 I don't think share any internal gear parts with the t56 as the sychro clutches are different. Not sure about the shift forks.
I'm sure they have shaft bearings with specs for play as well as countershaft end play IIRC. They're basically the same case but the syncros and gears do not interchange with a t56. Don't think the shift forks do either.