I can't prove it, but I think some of those holes are for aligning the parts for spot welding on the assembly line. I think the two larger ones in your first pic would qualify for that. To the far left would be for the bracket for the parking brake release rod.

I think the seat skirts use #8 sheet metal screws.


Kevin
1951 Chevy 3100 work truck
Follow this saga in Project Journal
Photos
1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car)
Busting rust since the mid-60's
If you're smart enough to take it apart, you darn well better be smart enough to put it back together.