History What is the difference. A question for mid 50s Chebby truck guys

I never thought to even ask about fenders. I have never noticed and I'll bet if I did I would think that someone altered one. But it certainly could have happened. If the assembly line was running and they ran out of first gen I do not doubt that they tossed the second gen bed on them rather that toss out good sheet metal and or stop the line.

There have been lots of that sort of thing happen over the years with both Ford and GM. I don't doubt the other manufactures as well.