KC-135E 57-2603 (c/n 17739) of 336ARW/AFRES at Fairford, July 1989. The KC-135E was an upgraded KC-135A, with P&W TF-33 engines of phased out Boeing 707's, that were slightly more economical (but still as noisy) than the engines fitted original. Today 57-2603 is a KC-135R with modern and silent CFM-56 engines, still serving with the reserves (now AFRC) 336th ARS.