[aerotruk63]

GM painted the trucks a special color for Government and the Military, and, if the client ordered I believe 6 or more trucks, their corporate color would be applied at the factory. Government and Military trucks could have had additional stickers inside the cab sometimes indicating who was authorized to operate the truck.
The standard paint code system had a 3 digit base color starting with a 5 then the next two digits defined the actual color. If it was two tone generally they added 30 to the two digit part to indicate the change to two tone. An example would be 522 for a base color Gray, Georgian. If the truck was optioned two tone the number changed to 552.
DuPont was the paint supplier to GM and according to the 63 Truck Data Book the code from DuPont for Grey, Georgian was 93-77784.

I see the radio opening has been carved, any other strange holes or parts added that you don't see on other burbs?

A 5600lbs GVW rating indicates that this burb was ordered with 17.5" wheels and tires.