The first time i had a drive shaft break on my 72 chevelle. Boy I tell you about the risk dummies like me use to take! stock chassis, 10.5" slicks, th400 w/brake 4500 conv and a 496cu bbc with a stock drive shaft. I go to high gear and fill something beating the floor to death! I lifted my feet so high from the floor my knees were probably hitting my chest! I didn't know what the hell was going on! totally changed the shape of the floor in that car. That's one car that found every short coming that I tried to get away with. stock axles - broke, stock drive shaft - broke, posi - broke, etc.!