I thought they used a 12 bolt untill '88. If not you can get one that will bolt right in. It would be a truck 12 bolt which the pinion isn't as big as a cars but the are still plenty strong. A freind of mine is pushing close to 600hp on a truck 12 bolt with a 35 spline axle upgrade, his is a '78. If you don't trust a truck 12 bolt, get one out of a car. The car 12 bolt are getting harder to find in salvage yards but the truck 12 bolts are a dime a dozen. I don't like the 9" bacause it doesn't use c-clips, the axles are a pain to get in and out.