I'm just making a quasi-educated guess about the model year, since World War II really made a hash of Detroit vehicle production. The best I can do is narrow it down to the 1941-46 range and hope for Chevy truck experts out there to ID year-specific features… which, of course, may have been swapped with junkyard trucks since the truck was manufactured. This was one of the few American vehicles manufactured for civilian sale in 1944 and 1945, though such trucks were considered 1942 models by The General.
I'm pretty sure this Chevy shares an owner with the '62 Corvair van; they park on the same block, both are generally loaded with painting gear, and each has a white-and-blue paintjob. The legendary Fieroborghini was shot just across the street, parked in front of the once-splendid Alameda Hotel.
You have to wonder how many miles are on this truck, and how many times- if ever- the engine has been opened up or replaced. One day I'll flag down the owner and find out.