Looking for rear sway bar mounts and rear shock mount plates for 71 Challenger that fit 8-3/4.
Try frank at Firm Feel in WA state.
They have full sets with mounting plates, hardware etc.
They also custom make sway bars to your eye-to-eye specs.
I purchased a 2" narrower rear bar n 7/8" diameter to work with my B-body width rear-axle and the !" offset spring hangers.
they also rebuild lower control arms.
Here's rear sway bar brackets https://www.kijiji.ca/v-other-auto-parts-and-accessories/thunder-bay/e-body-parts/1666770630