Mopar rears use axels that are the same length, this shifts the centerline of the rear yoke to the passanger side.
Ford and others center the yoke to the car. To do that one axle needs to be shorter than the other.
To use the Ford, the long side of the housing needs to be cut down to be the same length as the short side. And another short side axle needs to be purchased. The long side is either not long enough to be shortened and resplined or the second short side is cheaper to buy.
