A production line a first conveyor for advancing assembled vehicle seats to a checking station and a second conveyor for advancing each of the checked seats to a subsequent station, the nature of the subsequent station depending on as-built coordinates relating to each of the vehicle seats and determined by the checking station. The checking station includes a displacement mechanism and a detector. The displacement mechanism displaces a hip point fixture between a first standby position and a second test position in which the hip point fixture is depressed into each of the vehicle seats to simulate a load. The detector determines the as-built coordinates, at least one such as-built coordinate being determined from a location on the hip point fixture.