You'll find very few fine thread bolts on our trucks. A couple that come to mind are the door hinge bolts (3/8-24) and the engine mount to frame bolt and nut set (don't recall the size, but they're bigger than the door hinge bolts. Everything that screws into cast iron will be coarse thread.
BTW, the bolt part numbers in the FAM don't go anywhere that I've found, as the part numbers likely changed too many times. I've been down that rabbit hole a few times. Unfortunately the FAM #'s don't match up with those in Dan's Standard Parts Listing
It seems to me the bolts that hold the steering box on are fine thread. All but 1 of them. The one that threads up from inside the frame that threads into the box. I replaced mine with ARP bolts and weld nuts because I'm boxing the frame. I also bought a bumper to bumper stainless bolt kit for my 53 3100 that I could reference for you.
