NASHVILLE, Tenn. — RFK Racing will enter a third car in next year’s season-opening Daytona 500 for David Ragan, who will pilot the No. The number is part of Jack Roush’s heritage and was used in nearly 600 races in the second-tier Xfinity Series by Carl Edwards, Mark Martin, Greg Biffle, Chris Buescher and others. “The 60 car represents an …