Okay, bear with me here. I am not a transmission literate guy. School me please. What the heck are you talking about? The unit the guy has for me is a tail housing with a long shaft sticking out the front. This shaft has to go all the way through the transmission and out the front,....yes? So what yer saying is the shaft needs to be the same angles on the splines as the front of the trans where it comes out? Or what. I don't know a planetary gear from a ring gear. Pictures would be helpful...He says it's a "Late model" tail housing and shaft. So, seeing as mine is a 1973 it should work, yes?
