 This will be as a substitute for Leigh Diffey, his successor on IndyCar telecasts, who is unavailable that weekend.Jenkins will be available in a reserve role should Diffey be unavailable for other races, alongside Rick Allen, the current lead broadcaster for NBC's NASCAR coverage.Jenkins, still at the Speedway for the public address system, has also narrated some vignettes for NBC's NASCAR coverage on both weekday programs and race weekends.