How to tell you have OEM inner fenders - maybe

[71CHEVYSHORTBED402]

When I pulled the RH inner fender I found "they" had run a sheet metal screw into the outer fender instead of using the fixed nut in the "pocket" of said fender. Made me wonder, and it was suggested that is it was a replacement. Since then I did somewhat a dry run with the fender and inner fender off the truck (using a large exercise ball), and I see no reason why they did this outside carelessness.

The fenders were stripped, and I left them in the garage (don't do that). They were supposed to be done by now, but that's another story. Anyway, water got on them bringing rust, and I cleaned the worst of the two first. I used a rust remover concoction on the entire thing and sprayed it off with water DEFIANTLY DON"T DO THAT. I didn't want to leave it on there, for fear it would etch the metal. The result was a solid rust color (go figure). So I spent much time getting familiar with that fender.

I was a bit excited to see my RH inner fender had two stamps (pictured). Anyone ever seen these stamps? But to my disappointment, the LH fender doesn't have a single stamp. Couldn't tell you, but 100,000/1 the LH is original. I could be wrong, but I still believe they're both OEM. The reason is the braces spot welded onto the fenders are exactly the same. Even the holes are equally off-center where the brace is located front bottom inside.

On a side, this cleaning rust business wasn't a total waste. I discovered lacquer thinner and a scotch pad is your friend in these cases. The thinner breaks up the surface rust and comes off easy. I spent well over two hours cleaning up the rust on that RH fender. Took 15 minutes to do the LH fender.

I now keep them in the back room.