Attracting considerable interest at the Australian International Air Show 2015 was United States Air Force (USAF) Boeing KC-135R Stratotanker 54-1499 and 63-3553.
Based on the Boeing 707 airliner, the KC-135 Stratotanker is a military aerial refuelling aircraft and despite first entering service with the USAF in the late 1950's, over 400 airframes are reportedly still in operation to this very day ... what a remarkable achievement !
http://en.wikipedia.org/wiki/Boeing_KC-135_Stratotanker