You can be in the Air Guard/Air Force Reserves as an active duty retiree. You basically trade a day of retired pay for a day of military pay in whatever pay status you choose to participate in for that day's duty. You can even get promoted. So when you retire the second time, you get your current pay grade retirement check until age 60, then if you had time in grade to retire at the new grade you earned after your first retirement, your retirement check automatically recalculates to the new pay grade. If you don't get promoted, your check still gets bigger at age 60, based on the participation you did until you retired the second time. We have had at least three guys who got promoted as retired dudes at Laughlin. We have and have had several former USN/USMC folks, and we have several folks retired who still come in 6 days a month to fly. We have never to my knowledge had a retired interservice transfer. I don't know if it can be done, but it might be worth looking into.

PM me, if you have enough posts, and I can put you in touch with our folks who can answer that question.