I think there is a station still selling it off of highway 55 and Butler Hill on Lemay Ferry. Get off of 55 onto Butler Hill, go east 1 mile to Lemay Ferry, turn right and go south about an eigth of a mile and it's the station on the left/east side across from the funeral parlor. They used to have a posted street sign with the price.
If all else fails try calling Rob Wagner at Perfomance Autobody in Kimmswick 636-464-4686. He used to race and one of his employees is still running a chevy 2 at the track. Also try calling and talking to one of the guys at Jeffer's pro cars off highway 30 south of highway M.
Jim