All long-travel suspension systems add additional force to a drive axle. OE axleshafts are designed to twist a little before failure. The stock CV joint will typically hold up to twice the force of the axleshaft, so most companies simply offer upgraded alloy axleshafts that work with the factory CVs. Axleshafts can be made much stronger by using materials such as 4340 chrome-moly like the ones Rigid offers. For the ultimate in strength, 300M axleshafts are also available. Either way, the improvement in strength over the factory setup is significant. Just remember to peen the retainer nut at the relief keyway on the end of the stub axle once you have the hub assembled to it, otherwise this critical nut may back off over time, causing the wheel to loosen and eventually fall off.