I have a 1939 Chev COE also. There are holes on the right side of the cowl/firewall under the hood. But I think they were for the weight capacity tag? My truck had no tags on the cab, just those holes. I have been told that in 1939 Chevy used the engine block No.s for ID, but I have not seen proof yet. My truck came with a bill of sale only. But I have not been down to the DMV to see what they will say yet? My COE now sits on a P30 frame & is going through a complete up-grade.
O, by the way, I'm not sure what they called the frame rails in 1939, but a P30 frame is (Identical). My 1980 Chevy stepvan P30 frame rails are "Identical" to the 39 rails. If I had wanted to keep my cab on the 10" pedestal it sat on originally, my cab would had fit perfectly. The steering was there. Master cylinder with hydraulic booster off the van fit perfect under the short COE hood & every thing worked, using the brake peddle off the van. The front axle width is good also. But now I have independent front-suspension with power steering, power brakes, disc brakes in the front, with less chance of fatigue/cracks in the frame.
Do you have any photos?
By the way, do you got an extra grill???
Or maybe know were I can find some rear PU-truck fenders, 1939ish???
Have a gooder