(not mine) but hard to find and only a few left

That's what a slip joint is for. Besides, it's not like these cars have a body mounted on a frame. Not much chassis flex goin on.

C'mon Rusty. No chassis flex? Is that why everyone runs subframe connectors? Why high horsepower cars break the rear window? Why you can't bondo the roof/quarter joint without the filler popping out?

Factory stock these cars are flexy flyers. All you have to do is put the front end up on jackstands and look at the door gaps. If you really want to see something, just put a jack under one of the front framerails near the front bumper bracket and jack up the car until that tire is off the ground. Then take a look at the door gaps, or ask yourself why the other front tire is still on the ground. A little is balance, the rest is flex.

I like the Borgeson style u-joints, even installed one on my Duster. But I also added a slip joint, and did more than a little cutting and welding on the stock steering shaft to make it all work. That clip seems a little pricey for what it is, but if you want things to look even remotely stock I totally see how it would be useful.

This is what I did to mount a Boregeson vibration damping U-joint in my Duster. Probably overkill, but it addresses all of the issues, including any plunge in the system. And yes, that coupler is smaller in diameter than the stock one, and it clears my Doug's headers just fine.

http://www.forabodiesonly.com/mopar/showthread.php?t=228107