Sorry, but the first line at that link contains a common error, George and Jon.
A-D refers to the Advance-Design series of Chevrolet trucks. The series started in mid 1947 and ran through "mid" 1955. Chevrolet/GM officially referred to the series as 1947 through 1955-1st series of trucks.
It was Advance-Design not Advanced-Design, and Chevrolet/GM almost always hyphenated Advance-Design (that is why some of us use the abbreviation A-D). GMC trucks during that same time-period were called New Design (ND).
