 The launch customer of both aircraft, UPS Airlines would purchase 75 757s and 32 767s, more than doubling the size of its aircraft fleet.To update the oldest aircraft in its fleet, the 727-100QF conversion was introduced (QF=Quiet Freighter).In place of a hush kit, the QF conversion changed the aircraft from Pratt & Whitney JT8D to Rolls-Royce Tay turbofans.