Been there, done that. Wire wheel all of them nice and clean. Chase all the threaded holes and nuts. Chase all the bolt threads. Sort them by thread size, length and head style/head markings. This will show you the quantity of each. That's the key. When you start assembly it will be evident by size, length and quantity, most of the time, as to which ones to use. Bolts with flanged heads are usually for holding sheet metal parts not thick brackets or heavy components. Those items use bolts with flat washers and lock washers and sometimes nuts. Use NEW lock washers. It's not that hard. Look for around 3/4 to 1" engagement in most cases. Forget finding 1951 bolt part numbers and converting that to meaningful info., just put the truck together. Minor thing. I don't sort them either and I've done many trucks.
You must do all that thread chasing. It makes life easier. Those threads have been "resized" by a mixture of road tar, undercoat, grease, oil, peening, galling, galvanic corrosion, rust, thermal cycling and meteorite dust.
