A chassis cab is a type of body-on-frame motor vehicle design. Another term for the same design is cab chassis, which typically refers to a very basic vehicle that consists of those two components. Rather than being a complete vehicle with a flatbed, freight box, or other design elements, these vehicles typically have bare frame rails behind the cab. This can allow an aftermarket company or the consumer to modify the vehicle to suit their needs. A chassis cab may be modified into an ambulance, freight truck, recreational vehicle (RV), or for any number of other uses.
The two main types of motor vehicle construction are body-on-frame and unibody. A body-on-frame vehicle consists of a chassis that is structurally independent from the body, and unibody styles have bodies that are structurally part of the frame. Both cars and trucks used body-on-frame in the past, and chassis of both types could be obtained for custom coachwork. Unibody construction eventually overtook body-on-frame for most passenger cars, though many truck applications continued to use discrete, structural frames. This eventually made trucks the vehicles most likely to be available in chassis cab form.
Cab chassis can typically be obtained by either consumers or coach manufacturers, and then modified as necessary. A chassis cab may be sold to a coach manufacturer as incomplete, in which case the finished product may have both a build date from the factory and a complete date from the coach builder. Engines, transmissions, and other drive train component specifications typically correspond to the factory date, though there can be discrepancies from time to time.
The two main types of aftermarket coach builders are those that finish vehicles and ones that sell packages or components for people to complete their own chassis cab. Recreational vehicles are an example of an aftermarket industry that is focused on finishing chassis cabs for resale. Each recreational vehicle company may obtain chassis from many different vehicle manufacturers, and then finish them with their own unique designs. Many RVs that are built on light truck chassis will retain a cab identical to a truck or van of the same make and model year. Some companies that complete chassis cabs for resale use mass production methods, while others custom build each unit.
End users may also custom build their own vehicles from cab chassis. In some cases, they may fabricate their own parts to create the precise vehicle they want, though kits and prefabricated components are often available as well. This same process may also be applied to any other passenger vehicle that uses a discrete frame, and entire body conversion kits are available for some models.