 Structural improvements, avionics upgrades, electrical rewiring, airframe and systems refurbishment, and powerplant modifications resulted in low cost, low maintenance hours, and low spare parts consumption.The two TFE371-3A turbofans that powered the Skyfox together weighed 17 per cent less than the single J33-A-35 turbojet of the T-33, while producing 60 percent more thrust and consuming 45 percent less fuel.The TFE371-3A turbofan had a ten-fold increase in time between overhauls (TBO) compared with the J33-A-35 turbojet.