Remember that before the truck was your truck, it was his (or her) truck.
Lots of these old trucks were "engineered" literally in a field somewhere by guys who probably weren't ASE or Mr. Goodwrench Certified mechanics with a full selection of Snapon or Mac tools. They had some bailin' wire, a pair of fencing pliers, and a ball peen hammer.
Most repairs were probably originally intended to be a temporary fix, but since it seemed to work, they forgot about it.
Also consider who might have owned a 1950 pickup truck over the last 40 or so years.. probably not the social elite, or the well to do.. more than likely the flat broke people who didn't drive an old heap because they thought it was cool, but because thats all they could afford.
Combine that with the fact that most folks buying one of those trucks new were buying them not as a collectors item or a treasured piece of American history, but as a functional, no frills pickup truck. If they wanted a bumper to haul a trailer, they didn't order one from J.C. Whittney or the local pro-street shop.. they whipped out a piece of metal stock and got to welding.. the tape measure must have been out of reach in some cases, so they eyeballed it.
Trucks back then weren't fashion statements, they were used to push, pull, or haul stuff around.. alot of times by folks who were lucky to have some meat in the soup for dinner, let alone pay money to have their truck towed into town and repaired by a professional mechanic.
Both my '46 trucks have typical hillbilly repairs and/or modifications.. most done before I got 'em.. many done AFTER
To me, the hillbilly stuff justs adds to the charm of the trucks.. granted, if I find a part that was installed incorrectly and is not safe, i'll replace it.. but the home made spare tire holders made from old drums welded to both sides of my 1/2 ton are staying right where they are!