Maybe I misunderstood the earlier question, what you sent me Phil, they installed. My apologies if this is considered the "3rd member"

Here's a pic: ( Of the open diff they took out )

web page

I also checked as per Big Blue by getting under the rig and turning the driveline. I have 1/4" of movement +/- 1/32"
Sounds like that is unacceptable.

Update: Tow truck guy just came and took it off to a recommended drivetrain place. They're going to diagnose and call me back. Suggested it may have "dried out" from sitting waiting to install- and disagree that it couldn't be caused by pinion bearings as, in there oppinion, the bearings would whine both loaded and unloaded which is what is happening.