had that happen 2 times and it was wheel bearings both times

 

Ok..... I found the anwser today for our problem with the 35 - 40 shake. It's we have lost one of the weights on the back tire. Dealer told me that sometimes one of the weights will loose the glue and one of the weights will be thrown off. " He said to check both sides of the rear tire and you will notice a clear square spot / sticky spot where one of the weights were at. PROBLEM SOLVED ! .. So no problems with our front tires, shocks, or etc.....