Rear end shifted

I would get the rear off the ground and check runout on the wheels.

IMHO the rear took a hit sideways into a curb to bend the shakles and offset the rear that much.

I would also be sure the u bolts and perch centering bolt is in good shape. I have bought a few 8 3/4 with elongated center holes
I think you hit this right on the button. Now that you bring it up, I remember hitting a curb pretty hard a few years back and never thought anything of it. I had my rim straightened but didn’t think to check the rear end. Now I’ll have to pull some stuff apart and replace my shackles at minimum. Thanks danadart