I think SS/F was the lowest Super Stock class in 1968 so the Roadrunners would have run SS/F or SS/FA. As for the Stock classes, they ran E/S or E/SA in 1968 and F/S or F/SA in 1969. I had a '68 Sports Satellite 330 HP 383" 4 speed car that ran F/S in 1968 and G/S in 1969. Rated at 5 HP less than the RR and about 50 advertised lbs. more than the RR therefore one class lower. Were the 383 cars competitive. Mine was for awhile. Ran 12.60 on Carmen Rotunda's 12.73 national record. He eventually set the record at 12.34 and I was no longer competitive. I don't think the RR's were ever competitive in the class they had to run.