yeah... don't weld it!!!
also, for a cheaper option, check out Lock-Right ...
"The LOCK-RIGHT's operation is fully automatic. Designed to send the engine power to the wheels with the most traction, the LOCK-RIGHT will help get you where you want to go. While traveling straight the LOCK-RIGHT will lock the axles together similar to a spool. However, when the wheels need to differentiate in a turn, the LOCK-RIGHT will allow the outside wheel to rotate faster to complete the turn. The internal gears on the LOCK-RIGHT will overrun each other to allow this differentiation. " -
http://www.powertrax.com/lockright.html