I know in the early 60's when I was working for a Chevy dealer a guy would come and pick up cars and trucks and take them to be under coated and the cost added to the price of the unit with a mark up. Just like they did in the 70" with rust proofing and fabric sheild or the clear plastic seat covers in the 50's I think any under coating was dealer installed and not at the factory and that's my story and I'm sticking to it
Paul
