7 1/4 to 8 3/4 rear end swap. HELP!!!!!

Sounds like you have a B body 8 3/4 rear. Some folks say it's OK to just pull the springs out and just bolt it in. Will it work? Yes, but it is better to cut the perches off and weld them back on, or use new ones. In doing so it is important to maintain the correct pinion angle.

The disadvantage to just pulling the springs out, is it will prematurely wear the spring eye bushings.