389 electric mirrors

Well check your tires if the tires have a bad spot that will make it shakes if not well you gonna have to take it apart put some glue in the back of it but before the glue get your toll out and make sure it's tight then it's glue time

 

Take the cover off at the cab. Most likely the bracket the mirror arm sets in is broken.

 

May Be. Ones I've seen shake like that,it's the bracket behind the chrome cover that's riveted to the cab.

 

If the steering is not shaking my friend you need to get that glue gun and fire away

 

I agree with @062 but so far have had no vibration out of my mirrors they do whistle loud if I have the window down and I need to plug up those holes on the convex so the quit spraying water when they get wet please let us know if u figure out the problem