Farm trucks, otherwise known as a light truck, is a vehicle used to transport agricultural products from farmers in the farm fields. Originally, farm trucks are assembled by local truck workshops using used parts of cars scrapped from abroad. It causes a serious problem in terms of quality and safety, since conventional truck garages are lack of correct engineering principles in the assembly and there has a potential risk of accidents that may occur during use. This study is focused on enhancement of life quality and safety of farm truck users from different regions in Thailand. One problem encountered in the operation is that a clutch case to cover the flywheel-clutch-module, consisting of the engine flywheel and the clutch, is mostly fabricated without applying engineering understanding. This leads to time-consuming trial and errors manufacturing process and overweight parts. To achieve the weight and cost reduction of the overweight flywheel-clutch case, the concept design of the integrated flywheel-clutch case was proposed to develop a single component which combines the cover of the engine flywheel with the one of the clutch. Computer Aided Engineering processes such as structural analysis, mold filling analysis and solidification analysis were carried out to optimize the shape and the thickness of the designed clutch case. As a result, the volume changes during the solidification of ductile iron can be predicted. The proper design of risering system was obtained to avoid the internal defects, such as shrinkage porosity. The optimization enables a reduction of component weight by up to the half and decrease of development cost and time. The information of physical properties of ductile iron is used as the database for casting parts development in the long run.