Yeah, Russ is right. It depends on what rear and axle you currently have, such as a 57 1/4" length 1965 Mustang as compared to a 1967 59 1/4" Mustang rear. Measure the truck rear and axle for length, and decide if you have enough room in your wheel well to add an inch or so on both sides without rubbing with your current wheels and tires. Check out the connection of the yoke to the rear as Dave mentioned. Ask which gears that 9" has and if it is traction lock.