2009 w900l vibration

I pulled my fro18210c and installed a rtlo18918b to try and cure a slight vibration I was having due to what it ought was transmission. Now I have a much worse vibration. It is smooth up till 50mph,then when you hit 55-65mph it buzzes bad in floor,mirrors and steering wheel bad enough it will make your feet start tingling.
Here's list of things I've tried.
I had to shorten hanger shaft 3 1/8 inch it was trued and balanced. Even had rear shaft checked all good.
New clutch
Tried spacing hanger bearing down no change
Moved air suspension setting every way possible no change
I pulled front diff and power divider apart all looks like new
I put truck on jack stands pulled shaft going to rear diff to elimate it,pulled tires and brake drums. I run it up to 60mph shake just as bad.
So I pulled the whole drive line down and run it up to 60mph and its smooth.
I then put hanger shaft back in and it's smooth,so I put rear shaft in and it goes back to vibrating.
So I'm think it's got to be rear shaft but it was never cut. So I load the rear shaft back up and go to driveline shop and watch him check it. It spins up smooth as silk and shows about .003 wobble.
I'm about to pull my hair out. The trans is a reman rtlo18918b and can't believe that could be it as its smooth when the rear shaft is removed.
Drive line is spl250 and all joints are good.

 

It’s way worse with new trans. It was noticeable with old trans but nothing like this.
I set factory ride height and went from there.
I put truck on jack stands and removed the wheels and brake drums and run it up to 60mph on jack stands still vibrating.

It’s more in seat and floor but in steering wheel also.
Motor mounts are all good.
I can get under truck while it’s running 60mph on jack stands and the rubber doesn’t even wiggle in the hanger bearing so I don’t know.

 

She's in perfect shape. Even still has the rubber isolators on each end of the support.

 

I’ve already removed the rear rear axle shaft and locked the power divider and went down the road,there was no change.
Slip yokes,u-joints all tight. My old man is convinced it’s in the trans. I don’t have another 18 to try but I have a nice low mileage rtlo18913A I might try. I’ve never had a vibration I can’t find but this one has got me. My wife said what did you change and I said trans and driveshaft so she says it’s probably one of those then lol.

 

I'm going to play with angles more. The hanger shaft is 2 degree fall and rear shaft around 5 degree fall. Shaft are in time. Torque arms are like new all bushings tight. It had a very light vibration with 10 speed. When I got it out the input had some wear on bearing as it had more movement up and down than it should have. I thought I have found the problem but I didn't. With the 10 the vibration was not bad enough I couldn't use the truck. The vibration with the 18 has made truck unusable unless I want to run 50mph or slower. I've thought maybe the big bearing in back of main box could have play in it.