The ZF S6-650 is a 6-speed manual transmission

Manual transmission

A manual transmission, also known as a manual gearbox or standard transmission is a type of transmission used in motor vehicle applications...

 manufactured by ZF Friedrichshafen AG

ZF Friedrichshafen

ZF Friedrichshafen AG, also known as ZF Group, and commonly abbreviated to ZF, is a German public company headquartered in Friedrichshafen, in the south-west German region of Baden-Württemberg....

. It is designed for longitudinal engine

Longitudinal engine

In automotive engineering, a longitudinal engine is an internal combustion engine in which the crankshaft is oriented along the long axis of the vehicle, front to back....

 applications, and is rated to handle up to 705 newton metres (520 ft·lbf) of torque

Torque

Torque, moment or moment of force , is the tendency of a force to rotate an object about an axis, fulcrum, or pivot. Just as a force is a push or a pull, a torque can be thought of as a twist....

.

General Motors

General Motors

General Motors Company , commonly known as GM, formerly incorporated as General Motors Corporation, is an American multinational automotive corporation headquartered in Detroit, Michigan and the world's second-largest automaker in 2010...

 used the S6 as RPO

Regular Production Option

A Regular Production Option is a General Motors standard coding for vehicle configuration options. These codes are a combination of 3 alphanumeric characters and refer to a specific option or modification to the vehicle...

 ML6.

Gear ratios:

L	1	2	3	4	5	R
5.79	3.31	2.10	1.31	1.00	0.72	5.23

Applications

• 2001–2006 Chevrolet Silverado
  Chevrolet Silverado
  The Chevrolet Silverado , is the latest line of full-size pickup trucks from General Motors.-History:...
  
   2500HD and 3500
• 2001–2006 GMC Sierra
  Chevrolet Silverado
  The Chevrolet Silverado , is the latest line of full-size pickup trucks from General Motors.-History:...
  
   2500HD and 3500
• 1999–2010 Ford Ford Super Duty
  Ford Super Duty
  For the 1999 model year, Ford shifted the F-250 and F-350 truck lines to a design mechanically and cosmetically distinct from that of the F-150. The F-350 was not available for 1998, while the F-250 was available that year with the F-150's body...
  
   F-250, F-350, F-450 & F-550
  • 6.0 qt. mercon 5 or xt-m5-qs

Significance

This transmission will likely mark the last manual transmission

Manual transmission

A manual transmission, also known as a manual gearbox or standard transmission is a type of transmission used in motor vehicle applications...

 GM

General Motors

General Motors Company , commonly known as GM, formerly incorporated as General Motors Corporation, is an American multinational automotive corporation headquartered in Detroit, Michigan and the world's second-largest automaker in 2010...

 and Ford will use in their heavy pick ups, due to the advancements made in Automatic transmission

Automatic transmission

An automatic transmission is one type of motor vehicle transmission that can automatically change gear ratios as the vehicle moves, freeing the driver from having to shift gears manually...

technology and the low consumer demand of manual transmissions.

Construction

ZF first introduced the S6-650 in 1998 on the Ford Super Duty. ZF S6-650 – Heavy Duty 6 speed manual transmission has an aluminum alloy main gear case and tail housing with the bell housing integral to the case. The ZF S6-650 is built in both a 2 wheel drive and 4 wheel drive versions with a diesel design only. The S6-650 has an internal oil pump to circulate and cool the lubricant which is uncommon to a manual transmission. All gears on the S6-650 are synchronized with a dual cone synchronizer in 2nd and 3rd gears with an input torque rating of 520 ft-lb.

GM started using the ZF S6-650 in 2001 with some improvements making this 6 speed transmission different from the Ford version.