My IIIf has DRP directly under the Leica on the top cover. Another interesting note: My IIIf prefaces the serial number with Nr., the fakes seem to say No with a line under the o. I don't know if this is universal or not. Also remember that Leica II and III were concurrent models. The number denotes how many frame-lines the camera had, not a succesive series or model number, so they should have many of the same design details.