Tuning techniques for controlling three principal modes of elastic vibration-vertical, torsional, and lateral-in the frame/body structure of a heavy-duty truck are discussed. The components involved in the solution of the shake problem are the frame/cargo-body structure, the cab mounting, and the powerplant mounting. The method followed in this experiment was a three-dimensional mathematical model analysis using a transfer matrix. The theoretical estimates showed appreciable correlation with the experimental results obtained by using a electrohydraulic shaker system. This technique, based upon a study of the effects of various components on the three modes of shake, was applied to production trucks and produced quite favorable results.