The 1000 series is a line of 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...

s for on-road truck

Truck

A truck or lorry is a motor vehicle designed to transport cargo. Trucks vary greatly in size, power, and configuration, with the smallest being mechanically similar to an automobile...

s. All are 5 or 6-speed electronically controlled units and are manufactured by General Motors' Allison Transmission

Allison Transmission

Allison Transmission is an American manufacturer of commercial duty automatic transmissions and hybrid propulsion systems. Allison products are specified by over 250 of the world’s leading vehicle manufacturers and are used in many market sectors including bus, refuse, fire, construction,...

 division in Indianapolis, Indiana

Indianapolis, Indiana

Indianapolis is the capital of the U.S. state of Indiana, and the county seat of Marion County, Indiana. As of the 2010 United States Census, the city's population is 839,489. It is by far Indiana's largest city and, as of the 2010 U.S...

 as well as in Baltimore, Maryland.

Allison 1000

The Allison 1000 is rated to handle up to 620 lb·ft (841 N·m) of torque. Initially it was a 5 speed transmission, but a new "Generation 4" 1000 was introduced in 2005 that added a 6th gear at the very top of the ratio ladder, making it a double-overdrive like heavier duty Allison transmissions. For the 2006 model year, manual gear selection was introduced. This feature gives the driver greater control over the transmission, enhancing operation when engine braking or less frequent shifting is desired.
Gear ratios:

1	2	3	4	5	6	R
3.10	1.81	1.41	1.00	0.71	0.61 (06+)	4.49

Applications:

• Chevrolet Silverado
  Chevrolet Silverado
  The Chevrolet Silverado , is the latest line of full-size pickup trucks from General Motors.-History:...
  
  
• GMC Sierra
• Hummer H1
  Hummer H1
  The Hummer H1 is a civilian off-road vehicle based on the M998 Humvee, which was created by AM General. The vehicle was produced from 1992 through 2006, and was the first of what became the Hummer line...
  
  
• Chevrolet B-Series

Allison 2000

The Allison 2000 is rated to handle up to 620 lb·ft (841 N·m) of torque.

Gear ratios:

1	2	3	4	5	R
3.51	1.90	1.44	1.00	0.74	5.09

Applications:

• B-7 bus
• C-Series truck
• F-Series truck
• International XT Series