The Dream Event USAC vs WoO at the Springfield Mile

A Dirt Champ race, USAC vs WoO challenge race. It was a dream race with half the field made up of some of the top USAC drivers and the other half were top WoO drivers. Side note: If I am not mistaken. Little did we know this would be the last time we would see the World of Outlaws as a group drive non-winged cars? Even though it was in dirt champ cars rather than their own sprint cars. The last regular non-wing WoO Sprint race, may have been the April race at Knoxville Speedway of the 82 season? Anyone know the answer? (3.3.f)