Just as an fyi, 1939-1947 GMC data ID numbers on the are located in three places. (Not COE or FFC models?) On Chevrolet it was primarily on the passenger side under the hood, on the cowl just able the fender.

See ID info from the 1939-1947 GMC Master Parts Catalog:


http://i391.photobucket.com/albums/oo352/46Canopy/GMCDataPlates.jpg

Dale