Rolling chassis

A rolling chassis is the chassis without bodywork of a motor vehicle (car, truck, bus, or other vehicle), assembled with its final powertrain (engine and drivetrain), and able to move under its own power.
Heavy vehicles.
Separate chassis remain in use for almost all heavy vehicles ranging from pickup trucks to the biggest trucks and commercial passenger carrying vehicles.
The rolling chassis is delivered to the commercial body maker, coachbuilder, or bulk transporter on its own wheels, under its own power.
Automobiles.
Rolling chassis was a stage of manufacture of every vehicle. Mass produced cars were supplied complete from the factory, but luxury cars like Rolls-Royce were supplied as a chassis from the factory to several bespoke coachbuilders like J Gurney Nutting & Co who would supply a body to the customer's order (or build a car which was sold from their showroom). 
Automobile construction methods changed when unibody or monocoque combined chassis and body structures gradually replaced chassis.
Restoration.
In restoration circles rolling chassis is a name given to a bodyshell with wheels and suspension but without engine and transmission.