A loading tooling for thermochemical treatment of parts includes at least first and second loading stages stacked one on the other in separable manner, each loading stage including a rack extending in a horizontal plane. The rack is supported by four legs extending in a vertical direction with the legs of the second loading stage standing on the legs of the first loading stage. The rack has a plurality of support arms secured thereto, with the plurality of support arms of the first loading stage presenting an arrangement that is different from the arrangement of the plurality of support arms of the second loading stage.