On my truck the supports are also 7 3/4" center to center. The pads have a central hole for the support bolt.

You could make your own out of truck mud flap or similar material or order from various vendors
https://oldchevytrucks.com/me195.html

I am sure at the assembly plant the rolling chassis had the pads installed with the radiator. Later the front sheet metal would be placed. Since everything is connected, to install in an completed truck I think you would have to loosen all the bolts on the front end, remove the mounting bolts and pick up the shroud with a bar or jack.
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