Did GM ever put body filler on new cars. I have a 1967 RS camaro made in California. And in 1980 I was sanding off old original paint. After getting paint and primer off I hit body filler I thought there was have some damage. But to my surprise there was no imperfections to the metal. From one piece to the next lined up perfect so why was there filler in a car that was supposed to have the original paint job?

 

I believe GM has been using bondo type epoxy filler since at least 1955. Like you I sanded down some problem areas on my 55 Chevy before painting. I had a number of cracks in the paint, where I expected to find sheet metal damage. However, the sheet metal was fine. I believe it came off the assembly line with the fill a wee bit thick in two areas on the car where the cracks erupted. After 70 years, I can’t complain. I think the cracks scared away a lot of potential buyers who assumed it was a bondo queen; seller offered it so low I had to buy it.