I think the answer to my question will be no but I'll ask anyway. I recently purchased a 49 3100 pickup that was thought to be all or mostly original by the second owner. It's in great shape with some restoration but very little. But the engine serial number is a 1948 (216) but truck is suppose to be a 49. The ID plate is missing so I don't have a serial number for the truck. The gas tank fills behind the seat in the cab consistent with a 49.

Did Chevrolet ever put "leftover" 48 engines in the next model year truck or has the original 49 engine most likely been changed/replaced?