During 1971 and 1972, the GSX package became an option that was available on any Gran Sport. Production dropped in 1971 to only 124, and again to 44 in 1972. Many GSXs survive to this day and can be seen at the Buick Gran Sport Nationals held annually in Bowling Green, KY in the middle of May along with many other examples of '60s, '70s and '80s Buick performance models. Another Buick event is the Buick Performance Group Nationals which is held at National Trail Raceway in Columbus, Ohio early during the month of August each year.
The GSX and big-block V8 were dropped after 1974. In 1974, the GSX consisted of a trim package on Buick's small, X-bodied Apollo. Three engines were available on the 1974 GSX: the Chevrolet supplied 250 6-cyl.,and two Buick engines:the 350 2 barrel and 350 4 barrel versions.
Source: Wikipedia (original)