1970 - Richard Petty starts fourth, leads 134 of 300 laps and wins the Schaefer 300 at Trenton Speedway in New Jersey for his 109th career NASCAR Grand National victory.
From what I've been able to determine, this race is the only NASCAR Grand National / Winston Cup race ever sponsored by Schaefer beer. Its true that Schaefer is the one beer to have when you're having more than one. Apparently its not true, however, that the Trenton race is the one race to sponsor when you're sponsoring more than one. That distinction belongs to Pocono where Schaefer sponsored the Schaefer 500 Indy car throughout the 1970s.
Petty's victory in the Schaefer 300 has been well documented in this blog including: