There were a few significant seat changes over the life of the AD's, 1947-1949 was a cable seat but in 1950 (some late 49's) the width was increased by 2-1/2". Then in 1951 the new seat tracks with the rod were introduced. The tracks themselves were much improved as they had a better ball bearing system and were designed so spilled drinks did not gum them up. This style continued from 1951 through the 1955 1st Series.
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