You’re right gas dude. Those are aprons for a 47-53 GMC front end. They bolt to the front of the inner fenders and then the protruding vertical tab bolts to the outer fender and grill. There is also a center piece that bolts to the core support. Your pieces bolt to this as well.

Here are some photos: only one actually shows the pieces installed (black truck) while the one other shows the truck in primer and you can see exactly where those pieces would drop into place behind the front bumper pan.

https://photos.app.goo.gl/8ewMCybXiWmKCFNn8



1970 Chevrolet C10
Grandpa's -- My first truck -- In progress to shiny
Follow the build in the Project Journal
1950 Chevrolet 1-Ton Dually
"Ole Red Girl"
In the Stovebolt Gallery
More pictures here
1951 GMC 9430 1 ton dually--Shiny! | 1972 Chevrolet C20- Rusty- the puzzle box lid for the C10 | 1962 AMC Rambler American- my wife's
Parts trucks-
1951 GMC 9300 | 1951-GMC 9430 | 1951- Chevrolet 1300