8 3/4 swap

Mopar Tim said
Just got 8 3/4 rear end with sure grip, 3 55 gears. How much shorter does drive shaft have to be from 7 1/4 that is in now. Actually im picking it up tomorrow

Measure, measure, measure! Get the rear installed, set jack stands under the rear so the suspension is loaded.

Call a shop that you intend to use, ask THEM how they want it measured (from where to where). Take the DS to them and let them do their thing.