I put gears in for a friend of mine and am going to put the correct speedo gears in can i do it w/ trans in car(from the rear)??? I seem to remember pulling the tailshaft off and swapping out the two plastic gears, can i do this on these cars?

 

How about a exploded view of the back 1/2 of the trans? Can it be done from the back is all I want to know.

 

Yes, you can do it with the tranny in the car. As for exactly how, and for part #'s, ask here to get a quick answer, its a 93 specific board: http://sdf.mogmhp.com/index.php I think its just 2 plastic drive and driven gears that go in the tailshaft like you said, I did it a looong time ago....