I have the 1954 Southern ABA configuration and I have read the descriptions on the Tandem Associates site. The picture that is shown of an AB configuration has power pickup rollers on the B unit and also power Pickup rollers on both front and rear trucks of the A unit. Also the description given says that the A unit had the horn and battery in the A power unit. Every Southern F-3 (postwar) that I have seen, including my own, has the horn and battery in the non-powered A unit and the B unit has no power pickup at all. Also, both the powered and non-powered A units have power rollers on only the front truck. I know that other Lines F-3 units were built like the configuration shown in the picture but not the Southern or at least I have never come across such variations. Does anyone know if the Tandem Assoc. is correct, because if so, there are more variations than they list?

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).