The GMT800 frames were manufactured by Magna International in Ramos Arizpe, Coahuila, Mexico; and St. Thomas, Ontario, Canada.

Trucks were assembled in Oshawa, Ontario; Pontiac, Michigan; Fort Wayne, Indiana; Flint, Michigan; and Silao, Mexico; for pickup and 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.

This could be mixed and matched depending on the wheelbase, GVWR, and body type fitted to the platform, rather than a single-piece long frame.

A total of four front modules, seven midsections, and four rear sections were designed, and supported nearly 40 truck configurations.