I have a 3100 I purchased back in '95. The truck was last titled in Arizona and has a "newer" metal sticker on the cab door post that was probably put on around that time. There is no other evidence of an earlier door plate.
The truck was actually titled a '49 but judging by the existence of pull down door handles, vent windows and engine number, it appears to be a 1950. I've read about some years having a plate riveted to the firewall with production information, there is no plate on mine.
But there is a letter/number combination stamped in the engine compartment on one of the flats on the driver's side of the firewall. I haven't seen any info in chevy truck forums that might help with identifying what this number might be. It appears to be JBA308473 .
There are some faint outlines of what I think are military identification numbers on the front bumper, so perhaps this was a number added for their inventory records.
