It looks like an AC S-6 model filter (and, some versions of that style of filter were available when the truck was built/sold). (
SC-650 from 50-52). Is the conical bottom of the canister smooth (AC) or pinched-in at a few points (Fram).
Compare your canister to the ones in the excellent
Tech-Tip by ddauto (posted above). Tech-Tip link above.
If you post more photos and give dimensions maybe someone can help you figure out what your canister matches up to in the Tech-Tip.
You can certainly say "period correct" because an old-style by-pass canister oil filter might have been a factory option, or might have been added by the dealer/owner, or might have been added any time since 1951.
Are you as concerned about other things on the truck being exactly as it might have come from the factory?
