Ford Ranger rear end fit '71 Dart?

Sure the 7.5 axles will fit the 8.8 rearend, but they have a smaller drum register, so you have to run the smaller narrower drums and backing plates; which means you have more backing plate clearance to the springs. The Mustang 8.8 is usually smaller register, but four lug, just redrill the drums. But the four lug mustang axles are both same length ranger long side axle. (of the same year) Mustang is wide with a 1/2" right pinion offset. They say the 7.5 rearend is matched well with the 28 spline axles; sorta like the old 8" Mustang rearend from the sixties; with its 28 spline axles, and the 8.8 is better matched with the 31 spline axles, just like the nine is better suited for 31s.