https://www.twz.com/41988/shadowy-kc-135rt-special-ops-tankers-head-toward-afghanistan-as-evacuation-airbridge-forms

Back in my day, there were KC-135A models and Q models. The Q model was configured with separate tanks to refuel the SR71 with JP7 fuel. All the Q models were based out of Beale AFB.

Around 1982, the Air Force began upgrading the tanker fleet to CFM 56 Turbofan engines. I think they were formally airline aircraft engines. These re-engined tankers were designated as R models. In 1991, I got a ride on in our model on a trip to and back from Colorado Springs. We had a lieutenant colonel in my Air Force Academy liaison reserve unit Who was also in the reserve tanker unit at March. Every year he Arranged for a tanker or two to fly up to Colorado and bring home Academy cadets over Christmas. I hopped,a ride on the flight returning the cadets after Christmas. On the flight to Colorado, I sat back in the passenger compartment with the cadets. For the flight home, I arranged to get myself into the jumpseat up in the cockpit. The aircraft commander was a pilot. I knew back From my squadron on active duty. The navigator was a reservist. I knew back in the day. We used to sit alert duty together every so often. The takeoff out of Peterson field was like riding on a rocket ship compared to the old A models!