Final answer:
The driveshaft connects the transmission to the rear differential in the drivetrain, transferring power to the wheels in rear-wheel-drive vehicles. It is distinct from other components like the camshaft, crankshaft, and mainshaft.
Step-by-step explanation:
The part in the drivetrain that connects the transmission to the rear differential is known as the driveshaft. The driveshaft is a mechanical component designed primarily to transmit torque from the transmission to the differential, which then passes it on to the wheels. This part is essential for the motion of rear-wheel-drive vehicles, as it allows for the transfer of power. It is a long, cylindrical shaft that can flex or rotate to accommodate the movement of the car's suspension.
While the camshaft and crankshaft are important components of an engine, they are not part of the drivetrain that transmits power to the wheels. The mainshaft is a part of the transmission, but it is not the connecting component between the transmission and the differential.