Hello, I have a 74 Barracuda with an 8-3/4 and Mopar SS springs. The car has what looks like the Mopar front hangers with two bolt locations, and the springs are in the lower hole. I am getting a driveline vibration above 3,000 rpm/50-55 mph (the car has 3.91s). Checked the pinion angle and found it to be one degree positive.

I ordered a pair of four degree wedges to correct the pinion angle. The wedges are 3/8” thick at the midpoint, and I am assuming engagement of the center pin is going to be an issue. Does anyone know the length of the Mopar center pins? I’d like to pick up a new set in advance so I don’t make this into a two day project.

I have already done a precursory search and can’t find a length listed anywhere. I believe they are 5/16”. I’ve seen guys suggest using allen head bolts, although I have a few spring shops local to me so I probably won’t need to go that route. Would grade 8 allen bolts be sufficient if I do?

Thanks in advance.