GMT800

Main article: List of GM platforms

GMT800
Overview
Manufacturer	General Motors
Production	1999–2006
Body and chassis
Class	Full size SUV
Layout	FR/AWD
Body style(s)	4-door wagon 4-door extended wagon 2-door pickup truck 4-door pickup truck
Powertrain
Engine(s)	4.3 L V6 4.8 L V8 5.3 L V8 6.0 L-V8 8.1 L-V8 6.6 L V8 Turbodiesel
Chronology
Predecessor	GMT400
Successor	GMT900

The GMT800 was a General Motors full-size truck platform used from the 1999 through 2006 model years. It underpinned the Chevrolet Silverado and GMC Sierra pickups; the derived GMT820 and GMT830 were used for the Chevrolet Tahoe/GMC Yukon and the Chevrolet Suburban/GMC Yukon XL full-size SUVs, respectively. This platform was the successor to the GMT400 series of C/K pickups and SUVs, and was replaced for 2007 by the GMT900 line.

The GMT800 frames were manufactured by Magna International in Ramos Arizpe, Coahuila, Mexico and St. Thomas, Ontario, Canada. Final assembly of trucks was done in Oshawa, Ontario; Pontiac, Michigan; Fort Wayne, Indiana; and Flint, Michigan; for pickup & chassis cab models, and Silao, Mexico; Janesville, Wisconsin; and Arlington, Texas; for SUV models. The GMT820-based Hummer H2 was built under contract by AM General at a specially-constructed plant in Mishawaka, Indiana. A GMT810 2 door SUV variant was designed and prototyped, but was not put into production.

The GMT800 introduced a three-section frame system, which could be mixed and matched depending on the wheelbase, GVWR, and body type fitted to the platform, rather than a single piece long frame. The front section was hydroformed, while the middle and rear sections were roll formed or stamped, depending on application. This gives greater flexibility to the platform. A total of four front modules, seven midsections, and four rear sections were designed, and supported nearly 40 different truck configurations.

The GMT800 was the first truck usage of the then-new GM Generation III V8 engines. The 4.8 and 5.3 L versions featured iron blocks and aluminum heads, while the 6.0 L version used iron in both the block and heads.

Sales

Year	1999	2000	2001	2002	2003	2004	2005
Total sales	TBD	TBD	1,569,198	1,672,804	1,810,340	1,704,239	1,491,084

Applications

• 
  2003 GMT800 Cadillac Escalade EXT
• 
  2006 GMT800 Chevrolet Silverado
• 
  2004 GMT800 GMC Yukon
• 
  2002 GMT800 GMC Sierra

Basic platform	Years	Model	Notes
GMT800/880	1999–2006	Chevrolet Silverado	Some Late 06 models were sold as 07's and are referred to as the 07 Classic so as not to be confused with the New GMT900 Series
	1999–2006	GMC Sierra	Some Late 06 models were sold as 07's and are referred to as the 07 Classic so as not to be confused with the New GMT900 Series
GMT820	2002–2006	Cadillac Escalade
	2000–2006	Chevrolet Tahoe
	2000–2006	GMC Yukon
	2003–2009	Hummer H2	A unique platform, the front used a modified utility frame, the midsection was all new and completely boxed. The rear section used an upgraded frame for the 8,600 pounds gross vehicle weight.
GMT830		Cadillac Escalade ESV
		Chevrolet Suburban
		GMC Yukon XL
GMT805		Chevrolet Avalanche
GMT806		Cadillac Escalade EXT

See also

• GM GMT platform