Man, are you guys in luck! We have a Tech Tip in our very own Stovebolt.com Tech Tip Library that explains all this.

Tech Tip on AD differences

But to sum up, ALL AD truck cabs have the top cowl vent (in front of the windshield). All '47 through '50 have the driver's side side cowl vent. In '51, its function was taken over by the vent windows (in the door).

As far as I know, the GMC cabs follow the same evolution.

~ John

A kid raised on Hotwheels, Matchbox and Tonka cannot be reasonably expected to own only one vehicle as an adult.

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