Thanks Dave. Sometime in the past I remember seeing the page you referenced. It is in line with what I have always thought regarding the configuration of the Southern F3's. I am the original owner of the AA units and purchased the B unit fairly recently. By shear luck I received the Southerns because all the stores were sold out of the Santa Fe's and I have liked them from the start. Right now I believe the Tandem Assoc. information and pictures are incorrect and that the pictures may be ones of Southern shells on another lines configuration. I appreciate your digging in to my question. When I get some time I will post a picture of my Southern ABA and also of my 1946 Lionel 1409 O27 Set (also been in our family since purchase).