The medium duty C model vehicle uses many different manual transmissions. Because of the many different manual transmissions, only a brief description follows. For further explanation of the description and operation of a certain Eaton Fuller manual transmission, refer to the Eaton Fuller website http://truck.eaton.com/na/service_products/ or contact Eaton Fuller transmission for the transmission service manual. Transmission Technologies Corporation now supports the Spicer transmission service manual information. For Spicer transmission service manuals, refer to TTC website www.ttcautomotive.com. For correct identification of the transmission, refer to the identification tag located on the transmission. Refer to Transmission Identification in General Information. It is important to use the proper service manual and to order the correct parts for the specific transmission. Some models have different gear ratios and other internal components to meet the customer requirements. The transmission RPO will determine the correct components.

The FS4205B is a five-speed transmission. The five forward gears are synchronized. The 1st gear is a 6.99 ratio and the 4th gear is an 1.28 ratio. The transmission is used with engines up to 569 N·m (420 lb ft) torque.

The FS4205A is a five-speed transmission. The five forward gears are synchronized. The 1st gear is an 8.05 ratio and the 5th gear is a direct drive ratio. The transmission is used with engines up to 569 N·m (420 lb ft) torque.

The FS5205A is a five-speed transmission. The five forward gears are synchronized. The 1st gear is a 7.52 ratio and the 4th gear is 1.52 ratio. The transmission is used with engines up to 705 N·m (520 lb ft) torque.

The FS6305A is a five-speed transmission. The five forward gears are synchronized. The 1st gear is a 7.22 ratio and 4th gear is a 1.39 ratio. The transmission is used with engines up to 895 N·m (660 lb ft) torque.

The FS6305B is a five-speed transmission. The five forward gears are synchronized. The 1st gear is a 7.22 ratio and 4th gear is a 1.27 ratio. The transmission is used with engines up to 895 N·m (660 lb ft) torque.

The FS5406A is a six-speed transmission. The six forward gears are synchronized. The transmission is used with engines up to 759 N·m (560 lb ft) torque.

The FS6406A is a six-speed transmission. The six forward gears are synchronized. The transmission is used with engines up to 895 N·m (660 lb ft) torque.

The FSO8406 is a six-speed transmission. The six forward gears are synchronized. Sixth gear is an overdrive gear with a 0.78 ratio. The transmission is used with engines to 1 166 N·m (860 lb ft) torque.

The RT6609 is a nine-speed transmission. The transmission uses multi-mesh gearing and is not synchronized. Because the transmission is not synchronized, it requires a clutch system that utilizes a clutch brake. The transmission uses an auxiliary section to achieve a low range and a high range. The air control shifter shifts the auxiliary section. The range selection in the auxiliary section is synchronized. The transmission is used with engines up to 895 N·m (660 lb ft) torque.

The RT8709 is a nine-speed transmission. The transmission uses multi-mesh gearing and is not synchronized. Because the transmission is not synchronized, it requires a clutch system that utilizes a clutch brake. The transmission uses an auxiliary section to achieve a low range and a high range. The air control shifter shifts the auxiliary section. The range selection in the auxiliary section is synchronized. The transmission is used with engines up to 1 166 N·m (860 lb ft) torque.

The RT8908LL is an eight-speed transmission with 2 additional deep reduction ratios in low and reverse. The transmission uses multi-mesh gearing and is not synchronized. Because the transmission is not synchronized, it requires a clutch system that utilizes a clutch brake. The transmission uses an auxiliary section to achieve a low range and a high range. The air control shifter shifts the auxiliary section. The range selection in the auxiliary section is synchronized. The transmission is used with engines to 1 166 N·m (860 lb ft) torque.

The ES52-7B is a seven-speed transmission. The seven forward gears are synchronized. The transmission is used with engines to 759 N·m (560 lb ft) torque.

The ESO66-7B is a seven-speed transmission. The seven forward gears are synchronized. The seventh gear is an overdrive ratio. The transmission is used with engines to 895 N·m (660 lb ft) torque.