2019 Tahoe Vibration Irritation

[curbud]

Vibration Irritation

Have a 2019 Tahoe PPV with 91k on the clock. I feel a vibration in the seat / chassis.

Starts from zero and gets worse the faster I go. Mostly prominently felt above 75.

90 the whole truck vibrates. And vision starts to blur.

120 feels like it’s going to fall apart.

135 and I’ll enter into a new realm

I don’t think it’s the transmission. That feels solid. Although it’s a 6L80 so I’m sure it’s in my future. Don’t currently see any tach dance with lock up in 5th or 6th.

Work Done So far:

E85 flex tune
Oil
Trans fluid
Front and rear diff fluid
Transfer case fluid
X4 new tires
X4 new wheels
Pads and rotors all the way around
Driveshaft balance
X4 alignments
X3 shops that said suspension components and tie rods and what not all seem good and tight.

The last shoo today said the axle shaft flanges looked fine while spinning but the rear differential case is getting very hot after short drives?

I’m about to rebuild the diff and do shocks and struts for ***** and giggles at this point……

Help.