If I remember correctly those are small clutch head bolts that hold the window frame to the regulator. Do a search and you will see lots of previous discussions about "clutch head" screws and bolts on this forum.

Kent


1937 Chevy 1/2 ton
1942 Chevy 1/2 ton
1947 Diamond T Model 509
1951 Chevy 1/2 ton
1950 Chevy COE Model 5700 ~ "Barney" ~ And more pix