Ferris, I can't tell for sure where your antenna hole is from your close up shot. Below is a screen grab from a 1966 Chevrolet dealers handout showing a picture of a C10 with the antenna installed. Looks to be on a slight slope of the cowl extension panel from what I can see. Maybe this is helpful???
~ Dan 1951 Chevy 3 window 3100 Follow this story in the DITY Gallery "My Grandpa Carl's Truck and How it Became Mine" 1966 Chevelle (Wife's Hot Rod) | 2013 Chevy Silverado (Current daily driver) US Army MSG Retired (1977-1998) | Com Fac Maint Lead Tech Retired (1998-2021)
