It very well could be. Good points. If someone bent the gate badly and bought a new one in say 1970, would they have installed a GM reproduction gate? What would have been on there coating wise, flat black primer? 55 years of wear and tear on the body would look indistinguishable from 52 years of wear and tear on the gate. It’s an interesting question.
The tan 68 I pictured above (same tailgate situation) is clearly a repaint based on the grille and roof not being ivory. But the tailgate looks similar on the inside as the 67 in question. Now that I look closer at the light green 67, I don’t see the usual fading on the upper shoulders of the bed and fenders and roof. I am leaning more towards an old complete repaint.
I certainly am not claiming I know any more about it, just tossing out my perspective.
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I live in California, but identify as a Texan 
"If a job's worth doing, it's worth doing well"
Survivor "
Lil’ Mint" (67 c10 40k mile light green original paint)
Project "
C10 Fever" (68 factory black 396 swb)
Project "
Little Sister" (70 c10 blue original paint refresh)
Project "
Blue Bomb" (70 c30 blue original paint refresh)
SOLD
Project "
Vitamin C" (71 c10 orange original paint refresh)
SOLD