seat belt bolt size?
 

on the to do list this weekend it to make the shoulder mount for the seatbelts, whats the standard size bolt size and thread for this? I have a 56 BBW so its just round stock with a hole drilled in it.

this is what I have in mind from midfifty, but I can make the part easy enough and I did not order it in time.

1956-60 Ford F-100 Shoulder Belt Mount Insert, Big Back Window Cab