There could be clues, but all circumstantial:
1. CAB AND BED SAME ORIGINAL PAINT COLOR!!!!(under the layers) and it's Cameo correct and per paint code. Bingo! (Other models shared some Cameo two tone colors.)(57 should have a paint code plate)
2. Any chalk markings indicating 3124
3. Correct bed and etc.
4. Big rear window
5. "Custom" cab features.
6. Fender spear 3124
7. History/previous owners recollection or old pix.
8. Since there is no real way to tell, there no way to dispute someone who says its "not a clone". What would it matter to the value if it was all correct parts/accessories/features/original color? Nothing. But Buyer beware.


Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn