My 57 Custom 300 4dr has no seat belts in it. I have the floor all repaired and painted and wonder if anyone has ever put a shoulder strap to the center pillar to make it a bit safer to drive. I plan to put the lap belts in one of these days. Won't have it ready for the road for some time yet.
If your looking for original style lap belts, go to a store that supplies parts for small aircraft. Original style, quarter of the price.
I've just bought a set of rear seat belts from a VW Golf off EBay (two shoulder belts and a lap belt for the middle) and I plan to install these in my Ranchero as soon as they arrive. I'll post on here how I get on.