I think you are talking about a vent that is on the top center of the cowl between the windshield and the hood.
The name for that vent is a Cowl Vent.
Most cars and trucks had cowl vents from about 1932 to 1947.
I do not know about the Advance Design trucks. Maybe they had cowl vents up till 1953.
I also do not know when they stopped making windshields that cranked open.
I do know the 1935 Buick I had had a cowl vent.
My son's 1946 Art Deco has a cowl vent and the windshield opens.
I am sure those that know the exact years Chevrolet's had cowl vents and windshields that opened first came out and the last year they were made that way will be posting here.
