65MPH vibration

[Louis A Gentile Piano]

My 3500 SRW developers a vibration at speeds starting at 65 MPH

odometer is over 300,000 

It has been suggested That the propeller shaft my be out of balance.

Any one had a similar experience ?

if so what was your cure

[CamGTP]

Did you get the tires balanced first??

 

If so, then you are looking elsewhere like a possible driveshaft or axle issue.