Make/Year of Bed?

[kawecki]

I picked up this short stepside trailer today, for what I thought was a 60-66 chevy. I started looking at it closer, the round area's on the fenders appear to be emblem marks. Would that size/shape correspond to a 60-61 GMC? There is a Chevy tailgate on it and if you look close, there appears to be two other similar discolored spots on the tailgate. There is also a bar stock welded on the side rail of the tailgate that sticks out 90 degrees and is then turned 90 degrees with a hole through it, maybe for the chain? The overall patina looks pretty consistent. Anyone have any idea what year/make this is from?