What exactly does sYc stand for?

[GMH454]

A couple of posts in recent months have discussed Don's background. He first gained notoriety as a driver, and was favoured with special treatment from Chevrolet. Won several A Prod champs (from memory) in the East, and built his Corvair "Yenko Stingers" which dominated their class in the SPORTS CAR Club
of America competion. First Yenko sales literature is Stinger catalogs which refers to various hot packages. The first Yenkos were Sports Cars, hence the name.
(My lierature is at home so hope the memory is working)
The Camaros came later. In 1969 he would have been more famous as a driver and Corvair builder, the
Yenko Camaro fame came more in the 1980s