What a rare occurrence! At the 2011 America Truck Historical Society Convention in South Bend, Indiana, we found both a 1936 and a 1937 restored GMC truck with the correct grill --- each at different booths. You can go to every truck show for many years and never see even one. Therefore, we just had to get a few photos and make some comments. After all, this may never happen again. The 1936 grill consists of seven vertical .3' wide hollow chrome bars all the same size. The length is 25 1/4'. The notches in the receiving die cast pieces (hold the verticals in place) in the top and bottom are the same for each bar. By 1937-38 there was a change in the center vertical bar. It became wider. It changed from .3' in 1936 to .625'. It was also tapered back to align with the positioning of the other side bars. The overall length was shortened to 24'. The notches in the die cast top and bottom receiving pieces are therefore different due to the width change in the center bar. They may look the same on the outside but are not where they attach to the vertical bars. See photo. Chrome was not used to add to the appearance. These bars were painted silver.
1936 GMC Grill 1937 GMC Grill 1937 upper grill bar extension front view
1937-38 bottom view