The Gulfstream III, a business jet produced by Gulfstream Aerospace, is an all-weather, long-range, high speed aircraft powered by two Rolls-Royce Spey turbofan engines with thrust reversers. There are two types of GIIIs in service. Earlier model GIIIs have a DC based electrical system, these are referred to as Non-VSCF (Variable Speed, Constant Frequency). Alternately newer GIIIs have an AC based electrical system, and are referred to as VSCF GIIIs.