It's the only rear that is a direct bolt in other than a Mopar A-body rear. The only mod needed is the drive shaft which also needs to be shortened if your going from a 7 1/4 to an 8 3/4 or 8 1/4. They also sell a Ford to Mopar u-joint.
The Maverick/Comet rear is a little wider but can be used if you want an 8"