Two aircraft were built,powered by the Bristol Siddeley Orpheus engine as part of a USAF requirement for a utility transport. The Jetstar 1 first flew on 4th September 1957. The project was soon superseded by the four engined version. A Jetstar 1 still survives in the College of Technology at Vancouver Airport
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Jetstar 6/8

Jetstar 6 N55NC was never converted to a 731

The original long range executive jet, first flying in October 1960.  It was powered by four JT12A-8 turbojets. Many of the original versions have now been broken up, converted to -731's, or both.  162 of all original model 6's and 8's were built.  The -6 was the earlier version, although the two are externally identical.

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Jetstar 8 N55CJ 
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Around sixty of the original Jetstar's were re-engined with the TFE-731's by Garrett AiResearch and re-designated as the -731.  Apart from the larger engines, they are distinguishable by the large bullet between the engines, plus wing pods repositioned completely below the wing level.  These aircraft were given a sequential number by Garrett upon undertaking the conversion. The variant first flew on 10th July 1974.

Built in a new construction number sequence, the Jetstar 2 was an updated version of the -731 which first flew on 18th August 1976.  Most obvious external difference from the 731 was the addition of an air intake just forward of the tail.  Forty of this model were built, powered by 4 TFE731-3 turbofans  It can accommodate up to ten passengers.

Sixteen Jetstar's were built for the US Air Force, the C140A's used chiefly for flight checking and the C140B's as VIP transports, designated VC-140B.  All have now been withdrawn from use. < VC140B 61-2491