I was just wondering why Imperial was used for seatbelts hardware but nothing else. Sort of like the standard for TV screens and road wheels are go by inches. Unless of course it's those funky oddball metric rims/tires made in Germany used on Ford Mustangs back in the 1980s which makes finding new tires impossible to find.



I believe this is a mounting point. If I place a lock washer underneath the 10mm Allen head bolt and start tightening it down, once I get to the end, the lock washer puts enough pressure against the bolt it pops out. So the threads must just be coated with a 1 mm layer of paint making up the difference. Since 7/16 is roughly 11mm.

I'll try cleaning up the threads with a tap and see what happens.

I can get to the backside of the bolt through the rear wheel well to place a nut on it if I need to.

sure it is just welded on a plate there. Use good quality bolts otherwise you could just as well leave the belts out.

Well seems the 10mm acted as a tap and now the 7/16 bolts screw right in. So in summary, all four of these mounting holes must be for the seat anchors.