The six-speed Mercedes-Benz manual transmission is offered in two versions - the direct drive MBT520S-6D for trucks up to 40,000 pounds GCW, and the over-drive MBT660S-60 for trucks up to 60,000 pounds GCW.
The MBT520 has an overall gear ratio of 9.20, for engines that produce peak torque up to 520 foot-pounds. The MBT660 is for engines up to 660 foot-pounds peak torque, with an overall gear ratio of 9.18. The Mercedes-Benz transmission is compatible with medium-duty diesel engines built by Caterpillar, Cummins and Mercedes-Benz.