OH i forgot about the rear end, well what can i safely put the rear end through?

 

Depends how long has it been since it's been worked on, if the answer is never then being open means lots of tire spin and it could live a long time but wouldn't help when you race. If it was limited slip it could snap pretty easy considering its age but you never know, I would at least have it inspected and the fluid changed.

 

tell your bro to shut up...67' mustangs are more beautiful than anything from 1988.