I had a 1995 4x4 CTD that had a recall in 1998 or so concerning the factory steering shaft (in the column) unexpectedly separating into two pieces and the driver losing all ability to steer. There was a factory recall. The Chrysler "solution" was to wrap the lower part of the intermediate shaft in corrugated plastic and ZIP TIE (yes Zip tie) it in place. It was apparently designed to keep gravity at bay but collapse in the event of a front end collision. Something similar might work for the 1st gen/Borgeson/home-brew shafts.

 

Some DD shaft some u joints and one of these.
McMaster-Carr
in a nit welded to the sleeve part of the slip joint.

 

Any updates on whether the double U-joint shaft has been revised ?