After a century of experience in building hard-working vehicles, GMC can claim a top spot in the full-size heavy-duty pickup trucks, and the 3500HD Extended Cab was proof. The pickup-trucks have become more and more luxurious and focused on passengers' comfort. But there was a select range of vehicles that offered more than just convenience. They were designed to carry heavy loads, pull trailers with equipment, and help the owner put bread and butter on the table. Unlike its siblings with four doors, the regular-cab version was designed mostly for work, while the Extended Cabs were the middle road where a small team of five could travel short distances for a job. GM built the 3500HD version for work, and it showed it. Its front fascia was tall, fitted with big squared headlights and corner-mounted turn-signals. Depending on the trim option, the front bumper was black, body-colored, or chromed. The Sierra 3500HD Extended cab offered two doors at the front and a set of rear-hinged ones in the back. Like its Regular Cab version, it featured a choice of short or long beds. Inside, GMC installed either a bench for three or two individual seats, depending on the trim levels. The WT (Work Truck – base model) featured rugged vinyl floor mats and stain-proof upholstery. The SLT, top trim-level, offered a higher comfort level with individual seats, wood-trims, and a sat-nav system. In the back, the carmaker placed a bench for up to three occupants. GMC claimed that the most demanded version was the diesel version with its 6.6-liter Duramax unit that came with enough torque to pull a house and, thanks to the engine braking system, it saved the brake pads. All engine versions sent their power to the rear or all four wheels.