Mid cab vibration 80mph please help

[Patrick Greene]

Passenger seat shaking so bad I want to take it out / tire balance done / driveshaft looks good no dents , all weights appear to be in place. U joints good / changed front joint for grease option but they both had no slack /this is at 80mph/ tried shifting out eco mode no change at same speed /any and all wisdom would be appreciated

 

[Ratket]

Only at 80? — step to 90 and throw it into neutral and see if the shake is still there as truck slows down through 80.
If you are not comfortable doing this then don’t. After that maybe pull ur spare and start rotation it through from tire to tire and see if it cures it.

 

[Patrick Greene]

Appreciate I’ll get back