Stock NAS Defender 110's come with 10 spline front and 24 spline rear axle shafts which are strong enough to withstand normal off road and years of on road use. It is however possible for these to fail during locked and severe off roading conditions. Stock replacement units may be ordered from a variety of vendors.

To minimize failure during severe conditions, the stock Defender may be upgraded using A) differential air lockers to allow better traction under all terrain conditions (ARB offers both 10 spline and 24 spline upgrade kits including replacement differential at 3.54 Ratio, activation switch, solenoid valve, air line and bulkhead fittings), B) heavy duty axle shafts which improve the shaft's strength and contact area for both front and rear, and C) heavy duty CV (Constant Velocity) joints ready to support the heavy duty front and rear axle shafts. RoversNorth should have in stock all the parts you need.

After upgrading the differential center (by ARB or any other vendor) you may still experience failure of the crown wheel and pinion gears mainly because when differential is shock loaded, the pinion will push the crown wheel away as the differential centre flexes, once the pinion teeth start to ride up the crown wheel teeth gears can slip and shear some teeth off either gear. The solution offered by Ashcroft Transmission is to "Peg" the differential to hold the gears in constant mesh by putting a thrust pad behind the crown wheel, opposite the pinion, this means the pinion cannot push the crown wheel away.