Vortec 5.3L V8 SFI FlexFuel, 4-Speed Automatic with Overdrive, and 4WD. You win! Yeah baby! Set down the mouse because this 2007 GMC Sierra 1500 Classic is the truck you've been looking to get your hands on. It is nicely equipped with features such as Vortec 5.3L V8 SFI FlexFuel, 4-Speed Automatic with Overdrive, and 4WD. Don't get stuck in the mudholes of life. 4WD power delivery means you get traction whenever you need it. J.D. Power named the 2007 Sierra 1500 Classic as the highest ranked in Overall Initial Quality Design in its class.