I'm afraid I know little of 50's F100's but I have discovered something interesting. My "regulators" in my 67 Mustang were worn out. (Technically, the actual small shaft assembly is the "regulator" and the rest of the assembly is the "scissors". Commonly when people say regulator, they mean the entire assembly.) After some junkyard digging with my bad part in hand, I discovered the regulators in 79-93 Mustangs were absolutely identical. I only needed to drill out the three small rivets, swap them, and use new pop-rivets. Completely fixed my window problems with genuine Ford parts. Actually, I ended up using some from a Ranger as they had a slightly longer shaft which suited me better.
I hope you have similar luck. Certainly don't confine your search to just trucks, nor even to the 1950's. Sometimes Ford engineered a simple part that worked and obviously stuck with it, sometimes as long as 30 years.