Abstract: The invention provides a unitized cab-sleeper assembly that may be mounted on a truck-tractor chassis. The cab-sleeper assembly includes lightweight monocoque cab and sleeper modules that are mechanically coupled in a unique manner to achieve a unitary structure with great structural integrity, while also providing a comfortable ride, when mounted to a truck-tractor chassis. The cab-sleeper assembly includes in certain embodiments a unique ladderlike subframe, which consists of mechanically coupled separate subframes of the cab and sleeper modules. In other embodiments, the subframe is not ladderlike, and the cab-sleeper floors may be fabricated of a composite material over a lightweight core. Moreover, the rear of the cab is coupled to the front of the sleeper by concealed couplings, located at least at each corner of the cab-sleeper interface. In an important feature of the invention, each of the pair of sleeper mounts of the cab-sleeper assembly is located about midway along the length of the sleeper.