From what I have been able to find, the Mopar supplied kit to renovate the shaft with replacement shear pins is out of production and that any NOS kits that one may find have long lost their effectiveness because the chemicals have turned to soup.

The purpose of the screw is to eliminate any possibility of 'shaft creep' which in theory could cause the shaft to again shorten and pull up out of the Bergman supplied coupler leading to a complete loss of steering.

Competing disaster scenarios, being impaled by the shaft if I should rear end another vehicle or smack a tree, or have the steering wheel be completely disconnected from the steering box.

As previously noted by others, in most of our old Mopars, any perceived protective elements of controlled collapse of steering columns have long since evaporated.

I guess each must name their own poison. My choice is to drive this old car as though I am riding my motorcycle and maintain a very larger buffer about me.