The Engineering Features for '51 states the tire carrier was changed to the swingout type for all Series 3000 trucks. It states that when a truck is delivered with a wheel but no tire that a special bracket is bolted to the support bar to support the wheel.
Along with the taillight, the tailpipe was also changed. It was a bit shorter and curved down more to provide rear clearance. When the rear bumper option was chosen, the '50 and earlier taillight was used, since the license plate would be obscured by the bumper with the re-designed bracket.
Bob
