I was under the truck last night changing out rear sway bar bushings, and happened to grab the drive shift near the carrier bearing for leverage on the creaper. And I was rather surprised to find that the shaft moved rather freely up and down in the carrier bearing.

Is this normal? I figured it would be held in a much tighter arrangement

 

Is it the shaft moving INSIDE the bearing, or is it the bearing itself moving inside the rubber mount?

 

As far as I can tell, it's the rubber piece that's allowing the movement. I don't hear any metal on metal clunking or anything like that.