RPO 341 were installed at the factory { as evidenced by the factory assembly sheet }.
The side mount spare tire carriers were first offered as an option on the trucks in 1953
& would not be correct for a 1952 truck.
Although I have seen many side carriers that were painted body color... I have seen a lot that were painted black.
I would imagine that if the factory installed them... they were painted to match the body color.
I don't see any reason why you could not have had the dealer order a carrier for you but, if it was ordered from the dealer to be installed... it would have been black.