The 747 conversion story is very old and can be traced back to the mid-1970s. The Imperial Iranian Air Force (IIAF now IRIAF) bought several B747-100's from CO
. Some underwent conversion to what is now know as the 747-100SF with the side cargo role. A few had refueling gear and were used as air-to-air tankers. In fact, the oldest 747 still (supposedly) active as an IRIAF B747-131F built in 1970! The SFs of all series are going to be around for a long time.
Boland Aseman Jayegah Man Ast.