Large capacity shovels loading dump trucks with material in excess of 100 tons generates large dynamic impact forces results in high frequency shock waves, that in turn generates severe truck vibrations, and exposes the truck operator to significantly high whole body vibration levels and therefore compromises the health and the safety of operators. Previous studies have indicated a significant decrease in the dynamic impact force generated due to the gravity dumping of material into a CAT 793D dump truck by P&H 4100XPC shovel. However, none of those studies have shown whether or not the reduction in impact force at the truck body actually translates into a reduction in the vibration levels at the operator's seat. Therefore, in current research work, 3D virtual prototype for CAT793D has been used to conduct a detailed vibration analysis using MSC ADAMS to explore the effects of reported impulse force reductions results, on the operator's WBV exposures. Analysis shocwed that as the dumping height is reduced to 7.33, 6.33, 6.00, 5.50, 5.33, 5.00 and 4.9 m, the vibration level at the truck operator's seat reduces by 10.42, 15.51, 15.53, 15.73, 17.22, 18.85 and 19.61 %, respectively, as compared to the reported value of 3.56 m/s2. At an optimum dumping height of 4.90 m, the vibration level reduces from a value of 3.56 m/s2 to 2.86 m/s2. Therefore, current study shows that shovel dumping height optimization significantly reduces the vibration levels which improves the health and safety of dump truck operator's working under HISLO conditions.