I stumbled upon a guy parting out a '51 Chevy 1/2-ton today. I bought a complete under bed spare tire mounting assembly including the cross-braces for $20. I assumed this assembly was stock for my '49 because it is the same as the assembly shown in the '47 to '54 Factory Assembly Manual. Later I learned that this assembly is not original for a '49.

Will this assembly fit my '49 frame? Can the original parts for a '49 be purchased from repo vendors? How hard are these parts to find? I would like to stay with original equipment, but if the original stuff is not available, I might just install the '51 assembly in my '49. Thanks.