If I thought I was I was in that group of people you mention.. I'd say to you.. fk you and the horse you rode in on...but I don't think I'm in that category.
I always thought or knew them.. as a 5/16 med thread bolt. I think I would take them from a van, truck or car as well.. so that opens the door to more sources. I would bead blast or solvent them to raw, oil them and crew them in... then paint them over.
BUT I'm not a bolt expert..and my screen name is in regards to engines/mechanical mopar stuff.
Best of luck finding the bolts, I'm sure you'll find them ...if not...maybe the holes are stripped already from using the wrong pitch bolts.
