Sierra 2500HD SLT, 4D Crew Cab, 6.0L 8-Cylinder SFI Flex Fuel OHV, 6-Speed Automatic HD Electronic with Overdrive, 4WD, and Leather. Won't last long! Want to stretch your purchasing power? Well take a look at this terrific-looking 2015 GMC Sierra 2500HD. You just simply can't beat a GMC product. Prices do not include government fees and taxes, any finance charges, any dealer document processing charge, any electronic filing charge, and any emission testing charge.