Sounds like a cool truck. I always wanted to build something with an old chevy body like that.
I have some small knowledge of those from poking around at swap meets and such. Take it for what it is worth, you get what you pay for. lol. The 3800 would have been the equivalent of today's 3500 1 ton truck. I have seen them with a longbed stepside single wheel configuration with a 16.5 split rim as well as a dually cab chassis with a 20" split rim which is more equivalent of a ton and a half truck. They share the cab, doors, interior and hood with the 3100 1/2 ton truck. Grills, bumpers, fenders and steps vary. The basic 3800 I've seen had a grill just a little longer than the 3100 (I can't remember whether there was one more bar, or the bars were wider) as the cab sits a little higher and the longer grill filled in the gap to the bumper. Unless you have a good eye you don't really notice the difference unless they are side by side. The ton and a half variety has a much longer grill, different bumper and longer steps that drop farther down from the cab as the cab sits a lot higher than the 3100.
Does your truck sound more like the ton and a half variety, or is it closer in size to a 3100? I could have been a factory cab chassis or someone could have converted it to a dually somewhere along the way. If it is factory it would definitely have the split rims, if it has one piece wheels it is a newer conversion, or if it has single style wheels in the front and dually style wheels in the back it is a conversion.
Do you have some pics to share?
Here is a 3800 single wheel long bed:
ClassicTruckCentral.com | Classic Trucks For Sale | 1950 Chevy 3800 Truck For Sale
here is the dually version cab chassis:
ClassicTruckCentral.com | Classic Trucks For Sale | 1952 Chevy 3800 SERIES ONE TON Truck For Sale
I have never seen or heard of a dually with a stepside type bed, only cab chassis or flat bed.