I'm sure this has probably been covered here extensively, but I can't find it doing a search.

I've finally decided on a primer color for underneath based on scrubbing off a black coating that was on it all over with scotch brite & laquer thinner, but didn't find much in the way of body color overspray.

Am I correct in assuming that these bodies were painted BEFORE they were put on the chassis, so the body color overspray would be under the floor pans instead of on the chassis rails? I blasted and did the chassis on this car so many years ago that I can't remember anything about it now.

Also, at what stage in the assembly process was the undercoating in the areas like the trans tunnel and other factory applied splotches done?