C body 8 3/4 swap

perches are the last thing you weld up. Get the pumpkin centered, measure the flange end distances and then have the tubes and axles cut and splined. Weld the ends in or weld the sectioned tubes together, put it under the car and set it in the loose perches on top of the springs. Bolt up the shock mounts with the Ubolts and snug the bolts just barely. Jack the rear springs up so the tire just clears the floor and then you can rotate the housing to get your ideal nose nose down degree. Tack the perches into place, remove and fully weld them in. You can also have the tires on the ground and use a floor jack under the nose of the diff to raise it to the desired nose down at ride height tha tyour suspension is set up for.