I put in rear belts out of a late model Camaro in my '72 convertible. I used the factory anchor point behind the seats, which was for an optional shoulder belt. The new retractor gets bolted to that anchor point. I opened up the trim piece at the tops of my seats for the belt to pass through, or I could have purchased new trim pieces. My seat frames already had cut-outs in them to accept the belts, I don't know if all frames did or just convertibles. I just had to buy a guide and a trim piece where the belt actually passes through the seat. The stationary part of the belt bolts under the seat where the factory retractor bolts. I could supply pictures and part numbers if needed. There have been other posts on this subject, that's how I got some help. I purchased my belts brand new from a dealer. I didn't want to go with used ones, but a lot of people do. I've also seen quite a few aftermarket universal belts out there, which are cheaper.
