Az alábbi meghatározások alapján.
transmission tunnel:
A semicircular or oval bulge along the longitudinal axis of the floorpan to accommodate the propeller shaft and, at its front end, the transmission, enabling the shaft and transmission mounting position to be raised to the floorpan level, thus providing better protection for the drive train against road dirt and obstacles

body tub:
The bare body shell (minus the doors, trunk lid, hood, fenders) which is lowered onto the chassis at the time of assembly