One solution is to use loctite to retain the stub shaft in the passenger side axle extension housing. To remove the extension axle you will have to unbolt the extension housing from the pumpkin.

Or if your not comfortable using Loctite, a retainer ring could be fabbed up to hold the bearing in place. Several people who have LSD units used Loctite on the bearing... I never heard that they had any further problems.

My guess is that the forces on the axle are a lot higher with the locker. Those higher forces increase the friction withing the CV joint. As the suspension travels the force to move extend the joint is higher than the snap ring retaining force, so the snap ring pops out.

I'm sure that the entry angle on the back side of the diff could be a problem.

I would try locking the outer bearing into the housing.

Kevin