OldIHC

Hi all- first time posting here. I have a 1948 KB-3 my grandad used to haul wheat in. The bed is not stock (non-hydraulic/dumping also). I have taken the side boards off and just have a flatbread now. I’d like to re-do the flatbed with stake sides to be as original looking as possible. Is there a source out there for what the original dimensions would have been for the size of the bed? It is a one ton dually.

It sounds like it was a C&C when new (cab and chassie only) and fitted with a grain bed. So what you have is likely what it was when delivered.
There was a time, when grain elevators all had a hoist you drove on and the whole truck was tipped up so you didn't need a tilt/dump bed to haul grain. I still see some of these from time to time at older elevators, but they all are not used today, the OSHA rules have pretty much killed them off.
Around here, there is only one farmer that still hauls grain in straight trucks with gas engines! Most all is done in semi trailers with traps (hopper bottoms).

I can still remember my grandad hauling in wheat to Bungee and them blocking and lifting this truck!

I experienced that once or twice in the S120 I own also.

Dean