Rockwell chatter

Try taking it out of gear and coast at that speed. If the chatter still exists you can eliminate the transmission. First thing I would do in that case is look for cupping on any of your steer or drive tires, a sure sign tires are out of balance and/or you need a three axle alignment. Take it to a shop that will check all tie rods, bushings, shocks, springs, etc before doing the alignment. Tires that start cupping will become impossible to balance, unless you install Centromatics as I understand it.

If your suspension, alignment, and tires are in good order and you still have the vibrations. Start looking at your drive shaft. A bent drive shaft or bad u joints can cause this.

 

Go get your Ujoints changed out. It sounds exactly like it is a ujionn problem.

 

A grown man should not be showering with a girl born in '99, that's the first thing I got to say about that situation.

 

Sounds like driveline.

Check all u joints. Also make sure your leveling valve on rear suspention is working correctly and adjusted as per spec...

 

Last time this happened to me my main drive differential ate teeth. But this was after 2 days of symptomatic whining noise.

 

Who was doing the whining?

 

The drive differential.