 The Skyfox was marketed either as a complete converted aircraft from Boeing, or as a conversion kit, with the customer providing the T-33 airframe.The conversion incorporated about 70% of the existing T-33 airframe, but replaced the existing internal single Allison J33 turbojet engine with two Garrett TFE731-3A turbofan engines mounted externally.Together, the two TFE731s weighed 17% less than the single original engine, while providing 60% more thrust on 45% less fuel.