Abstract: A lock assembly for locking or unlocking the door of a truck or trailer body from a handle located inside the cab of the tractor. The tractor cab is fitted with a pivotable handle lever mounted on about fixed rachet gear engaged by a pivotable tooth on the handle lever, with the handle lever linked by a lock rod that extends under the floor of an attached truck or trailer body to a latch fixed on the door of the truck or trailer body. The lock rod may be fitted with coupling means for separation into a tractor section and a trailer section for use when the trailer section is detached from the tractor. The door latch is in the form of a bolt slidable axially through an eye member fixed to the truck door or alternately the bolt is bent at an angle to rotate about a fixed bracket on the door, with the bolt coupled to the lock rod by helical-slotted collar that translates reciprocal axial motion of the lock rod into rotary motion of the bolt.