For light duty truck, frame is one of the major structural systems and it must go through a series of duty cycle proving ground events to meet durability fatigue performance requirement. Nowadays, in order to meet stringent CAFE standards, auto manufacturers are seeking to keep the vehicle weight as light as possible. The weight reduction on the frame is a challenging task as it still needs to maintain the strength, safety, and durability fatigue performances. CAE durability fatigue simulation is widely used in frame design before the physical proving ground tests are performed. A typical frame durability fatigue analysis includes both the base metal fatigue analysis and seam weld fatigue analysis. Usually the gauges of the frame components are dedicated by the seam weld fatigue performance so the base metal could be over designed. One of the methods to reduce the frame weight is to cut lightening holes in the areas that have no or minimum impact on the frame durability fatigue performance. In this paper, the authors proposed a new methodology to systemically identify the locations of these non-critical areas that can be punched for slots or holes, while maintaining good durability fatigue performances in both base metal and seam weld joint. A light duty truck frame is used to demonstrate the efficiency of this process. Through this approach, the authors were able to reduce significant amount of weight on a well-designed frame without compromising the frame durability fatigue performances.