[rgunlock]

I guess the nut is replaced rather than being held from backing off. This is from the AA website:

GM 32 TOOTH 4WD OUTPUT SHAFT
On all NV4500s that were equipped to a GM 4WD transfer case, you will find that the output shaft has 32 teeth. The adapter housing that is mounted to the back of the transmission case is 8-1/8" long. On the inside of this tailhousing, you’ll either find a vibration damper on the output shaft or a steel sleeve. Most of our transfer case adapters will require the damper or sleeve to be removed. We couple to the 31 tooth spline located under the damper or sleeve. In order to remove the vibration damper or sleeve, you must use a special socket. This socket will be required in order to remove the nut because this nut is put on with 275 ft./lbs. of torque. On transmissions with the damper, a gear puller will be required since the damper is a press fit to the output shaft. On all applications that require the removal of the damper or sleeve, we will provide a custom set collar that must be installed on the output shaft to retain the 5th gear into position.