Gear Engineers have long recognized the importance of considering system factors when analyzing a single pair of gears in mesh. These factors include: load sharing in multi-mesh gear trains@ bearing clearances@ and effects of flexible components such as housings@ gear blanks@ shafts@ and carriers for planetary gears. Quality requirements and expectations in terms of durability@ lower operating noise and vibration@ and efficiency have increased. With increased complexity and quality requirements@ a gear engineer must use advanced system design tools to ensure a robust gear train is delivered on time@ meeting all quality@ cost@ and weight requirements. As a standard practice@ finite element models have traditionally been used for analyzing transmission system deflections@ but this modeling environment does not always include provisions for analysis of vibration@ efficiency@ or any considerations for attribute variation. And that often requires many runs of the test to ensure all variations have been included and tested. An advanced software tool is available for the analysis of transmission system durability@ noise@ vibration@ and efficiency@ all within a single programming environment@ including the effects of flexible components such as housings@ gear blanks@ and shafting@ while also allowing manufacturing variation studies to be performed. This paper includes the results of a case study of this program.