I'm in the process of fitting new belts in my 1200 Coupe and I have succeeded in the front but am having difficulties in the back. I had no belts in the back seat previously and have found mounting holes for lap belts but was wondering if I could install lap sash belts. I was wondering what the purpose of the two wholes with threads was on the walls of the coupe's boot space??? My bolts are too big for the threads.