If your vehicle is so equipped, a two-speed drive axle allows you to select a lower gearing for greater torque at lower speeds. When you park your vehicle, you want maximum torque from both the transmission and the two-speed drive axle to prevent your vehicle from rolling, should its brakes fail. Place the transmission in the lowest forward gear, if parked facing uphill, or reverse gear (which is also a low gear) if parked facing downhill, or park if the vehicle has an automatic transmission. If the vehicle has main and auxiliary transmissions, place both in gear. If the vehicle is equipped with a two-speed axle, the axle should be in low range.