Challenger 8 3/4 Rearend

All that is needed to mount it, is to relocate the spring pads to match your car, then narrow as desired. With the right backspacing on the rims, I have heard of guys using them without even narrowing.( I think this might look funny).
Also check your pinion size. It might be larger than your original, but Spicer makes a u-joint to adapt them.