Sometimes the tires don't slip enough. When the car was build he put in the lighter drilled axles. Second outing at Laguna Seca and it snapped one making the left hander into the corkscrew. Now it's got the solid NASCAR axles in it.
And, with "Locking" or "Locked" type units the axles, each individually, must be capable of the full torque capacity transmitted from the drivetrain, to the total capability of the traction of the singular tire which may present traction, as these units will provide either a 50/50 division or 100/0 torque transfer to which ever tire/wheel resists motion.
Hence, any of these being utilized will in the advent of one axle failure transmit 100% torque to the remaining intact axle (up to the limitation of tire to road surface traction) and this will general create a torque-steer phenomenon unless the remaining axle instantly fails from the overload. This not being so prevalent in the "slipping" differential units because despite the claims of their ability to "transfer torque to the wheel with traction", they are truly only "resistance" to the differential action, and generally the "friendlier" they may present themselves, the less capable the prove to be.
On the torque steer phenomenon, I had an F350 4 X 4 P.U. I used to off-road regularly, and a broken axle was common enough we would often even carry a spare to change-out in the field so to speak. I had "Lincoln-Lockers" facilitated front and rear in this truck, and when it would break the rear driving axle, the advantage to the 4 X 4 (and the "full-floating" axle assembly) was one would just engage (lock-in) the front axle and drive home, no wrecker required, but with the "locked" front axle one could not steer the truck with both axles locked-in on hard pavement, so I would just lock-in one side driving with a one wheel drive on the front steer axle of a four wheeled vehicle. This worked fine with "very" progressive application of the throttle for acceleration or deceleration function, but if abrupt the truck went left or right, like it or not, depending on which: accel or decel and which one axle was locked-in!
And this driving challenge would general be at the end of the day, with the beer cooler being nearly empty (remember always take more supplies out into the field then you'll need)!
Scott.