In 1968, Heuer redesigned the case used for the Autavia from a screw-back to a snap back compressor case. A compressor case was a patented case designed by Ervin Piquerez who sold these cases to a few watch manufactures, the compressor case has a unique seal construction which ensures water resistance through pressure on the gaskets and the crown. The principle is rather simple, deeper the watch was immersed, the more pressure on the case, the tighter the  case and more water resistant the watch.However, despite the new case, the Autavia retained its original water resistance of 100 meters or 330 ft. the case was larger at 40mm. 

The Autavia 7763C, was the snap back evolution of reference 3646,  a two subdial manual wind  caliber Autavia with a screw back case which was often worn by Mario Andretti.

Mario Andretti was the 1978 Formula One World Champion, a won many famous car races in the USA including the Indianapolis 500 in 1969 and the Daytona 500 in 1967 most likely wearing a Heuer Autavia.

 This 7763 Compressor here Autavia is in splendid condition with beautiful patina on the tritium markers. the dial has some gloss. the case and bezel appear untouched and are very sharp. the Bezel teeth are particularly sharp. A classic example of an Autavia for the most sophisticated collector.