For optimal torque delivery as a function of cost@ there are critical parameters that need to be communicated to the gear designer from the mill builder when designing gear drive systems for ore grinding applications. Apart from loads and speeds@ interface dimensions and site specific conditions are also needed. Deciding up front which gear rating practice to select can affect the torque capacity of the drive train by ~15%. How to deliver the torque to the mill pinion@ either by a gear reducer or low speed motor@ influences the distribution of cost between the prime mover and the gear train. This paper will outline the design considerations that go into construction of the drive system in order to explain why specific data is required and where design freedom is necessary. A clear specification up front that allows for matching interface dimensions while allowing for the most cost efficient up front design achieves this goal.