re: B-52 Stratofortress, how is it still in service?

I served in the Air Force from ‘69 to ‘73 as crew chief on KC 135 tanker. One of the most impressive sights I’ve ever seen was a B 52 coming up behind very slowly for an air to air refueling. That massive aircraft hooked to us by a boom and us fueling him up. Then disconnecting and just as slowly dropping away. Refueled several type of aircraft back then but none quite like the B 52.