40mph thrashing noise

[BeerCan]

Having a noise in the growler that I would like help with diagnosing. It's the same as this

Why might I have a loud thrashing noise coming from the transmission area that starts at 40 mph? It will even thrash when coasting down a big hill as long as I am going over 40 mph. I had noise at slow speed when I first got the M1161 that was due to the bent skid plate. I removed the skid plate that was rubbing front drive shaft that looked undamaged and that low speed rubbing noise was gone.

See further info here if you like
https://www.growlerforum.com/forum/garage/engine-and-transmission/3862-tranny-noise

The person with the other growler has replaced parts and has had everything rebuilt and the noise came back. I am hoping someone here has the knowledge to help figure this out.

Front axle is a Ford 8.8 with a eaton truetrac. Transfer case is a New Process NP241OR.

If it stops raining I am going to take the front driveshaft out to see if the noise goes away.