If you need a commercial-grade truck, you're probably looking at cutaways--medium- to heavy-duty chassis cabs outfitted with customized "toppers" that fit onto the flatbed. The GMC Topkick C4500 can be configured to various commercial applications. Most comfort features, such as air conditioning, are extra. Engine choices including a Vortec 8-liter V-8 gasoline engine with 325 horsepower and 450 pound-feet of torque, and a 6.6-liter V-8 turbo-diesel engine with 300 horsepower and 520 pound-feet of torque. The six-speed Allison transmission is also standard. The Topkick C4500 costs between $27,890 and $41,935. Alternatives? Check out the Chevy Kodiak or Dodge Ram 4500 Chassis Cab.Jill Amadio is an international award-winning automotive journalist and author.