The earlier Advance Design (AD trucks from 47-54 had cowl vents to let fresh air in. From 47-50 this vent was on the drivers side just in front of the door. 51-54 they moved that vent to the top of the cowl just in front of the windshield, behind the hood. I just happened to see two GMC trucks that have both! I didn't think that even existed. I have never seen it before much less two trucks that have both vents in the same day.
