Well heres my 2 cents worth..lol..I copied the pic and blew it up, it lots to have a inline 6, the air breather is to one side , I used to operate a 39 chev boom truck in a wrecking yard and to me thats what it looks like..the ford in these years mentioned are more round in the cab roof, had a few 36 37 ford cabs...Either way hard to find mid 30's cabs not matter what it is..

I am a old truck nut and had my 37 Chevy over 30 years now.Allso sold a 36 Ford and 38 Chevy pickups a few years ago.Man thats a small pick for these 62 year old eyes.Looks to me like just the fender brace on the right and no grill.I guess 1941-46 Chevy or GMC.1939 was first year for split wind shield in chevy.Grill and head lights make them easy.This sure is not easy.