John McGinley is in his mid-sixties. It's been a long time since I saw an episode of Scrubs, and I always just caught random reruns, never saw it straight through, but I don't remember anything establishing Cox's age.A refresher for those who have forgotten, but we had an entire episode where the plot was Dr. Kelso was being forced to retire because policy is once you turn 75, you have to retire. Kelso had bosses, and even if Cox took Kelso's place, he's still have bosses and it would be highly unlikely he'd get them to change that policy.
Ah, Scrubs is one of the shows where Wikipedia deigns to have a page on a fictional character. Cox is a year younger than McGinley is IRL.