The map on page 275 in The Railroads of the Confederacy shows the ferry but does not identify the exact location, just that it is on the Tombigbee below McDowell's Bluff and Demopolis. I have seen a description of the operation somewhere. I think it may be in the recently published book on Alabama railroads. If any one has a copy, please check. Mine is locked up in the office. I'll check Tuesday when we are allowed back in. I'll try that head smacking thing, may work for me too.
Bob