Has anyone installed this setup in a 64 to 67 El Camino.

I put a set from Morris Classic Concepts in my 66 coupe if that helps. Very easy install. Got he matching set for the back seat. Very good product. Click on "Web Page" in my Sig then on the "Interior" picture for photos of the belts installed.

I put some Autoloc belts in my 65 EC. I made metal plates that I bolted behind the a pillar for the upper mount and next to the door sill for the lower outside mounts.