What could cause the rear to sit lower on one side?

[JordanZ28]

All brand new. In fact, I've done every piece of suspension over the past six years. The only thing that wasn't replaced were the rear shackle bushings, but they weren't in terrible shape.

Did you solve it , as I notice this on my 78 recently.

 

[Lee45]

I had the same problem a few years back, ended up being that one of the tubes on my rear end had broken loose and twisted. Check the angle of the spring perches with a yard stick. It was obvious for me since I had slapper bars at the time.

Ended up pulling it out, welding it with silicon bronze tig wire and just cutting the perches off and welding on new ones. Worked out better as my perches weren't centered anyways