General Motors has quietly released their 2010 Fleet Vehicle Guide to dealerships, and it seems that big changes have occurred under the hood for their Silverado pickup trucks.

GM seems to have dropped their 6.0L Vortech V8 from the engine line-up for the 2010 Chevrolet Silverado 1500 and GMC Sierra 1500 pickup trucks from normal production, but will continue to use the engine for their two-mode hybrid pickup-truck lines. The old 6.0L will also be available on GM’s heavy duty 2500 and 3500 series pickup trucks under the Chevy and GMC banners.

Other engine options for 2010 include a 4.3L Vortec V6, a 5.3L FlexFuel V8 and a 6.2L Vortec FlexFuel V8, along with a new 4.8L Vortec Flexfuel V8.