I just purchased a 1950 flathead v8. I had 2 to chose from (not sure of the other year but my f5 dually is a 1950). I picked the 1950 engine as my engine has a cracked block. I paid $300 for it and supposely it runs good. He advertised the two engines as one having "narrow" pulleys and one having "wide" pulleys. The one I picked has the narrow pulleys. What's the difference? If my f5 has wide pulleys will everything interchange onto the new engine? Thanks!
Trucks ran the wide belt pulley while the narrow belts were found on cars. The engines are identical for all practical purposes, and with the 50 engine you should have hardened valve seats which is a plus. If you bought the engine complete (including fan, generator, etc.), you can run it as is. If all those goodies are absent, you could swap the bolt on belt accessories from your cracked engine since all flathead blocks are the same (48-53 US trucks).
Check to see if the fan lines up with your radiator shroud. As long as the engine runs with no cracks or other problems, I'd say you did good. - tim
You might also want to check the distance between mounting
holes on the narrow belt water pumps. I tried to drop in a
motor with them once in my 52 and they didn't match up with stock
motor mounts. Barely missed so I had to change out the water
pumps to the wide belt for the truck. Good luck