a plant for assembly of bodies with work stations and conveyance devices for conveying bodies between work stations . the conveyance devices include reference members assembled transitorily on the conveyance devices to support the body on the conveyance devices during transfer between work stations . grasping devices are assembled in the work stations for grasping the reference members and positioning them accurately while temporarily disengaging them from the conveyance devices to accurately position the body supported on the reference members in the station space . the reference members include a grasping device to grasp the body and holding it steadily against them when operated by actuators assembled in the work station .