I am hoping to get some help in identifying my inherited Walker. It was purchased around 1970 by my father. I have read up on this subject, and some people have indicated that quite a few were made without any manufacturer I.D. I have some memories of the box that it came in, but that box is long gone. I was wondering if there are slight differences which could indicate who the manufacturer was? Since I hear that parts are not interchangeable between manufacturers, it seems like there should be some way of telling who made this replica. Photos show only markings I can find. Any help appreciated.