The side mount spare in 1954 was a factory option.

http://chevy.oldcarmanualproject.com/parts/1929_54/441.htm

I think the first year it was a factory option was 1953. Since the 53 and 54 bed-sides were different, I'd bet the 53 and the later wheel "hangers" were different, but the fenders with indents might have been the same?