General Motors: The G-series, sold as the Chevrolet Express and GMC Savana, remains GM's main product in the cargo vans segment. Its body-on-frame design includes traditional powertrains, including a gasoline Vortec V-6 and three Vortec V-8s (4.8-, 5.3- and 6-liter, with CNG and propane conversions available for some), plus the 6.6-liter Duramax V-8 diesel, mated to 4- and 6-speed Hydra-matic transmissions.
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