55.2-59 Door hardware not matching

[washington blue]

Hi guys, I'm working on my 55 and I have two different doors on it. The driver door is original from the 55, the passenger door is from a different truck, year unknown. The interior door trim panel that covers the window and door mechanisms is held on with about a dozen screws/bolts with a Philips head. My problem is the 2 doors do not match, passenger door is simple 1/4 inch bolt size. Driver door is smaller and I do not know what size it is, or thread count so I don't know what to get. Anybody know what these smaller bolts are? The old truck companies offer bolts but do not state size, thanks, Norm