My 49 fastback was purchased new at Warren Cadillac in Minnesota and having never found any information about the dealership since my 2007 post below, I goggled Minnesota Historical Society this am after reading Philippe M. Ruel post on dealerships that gave me the idea and here's what I found.
http://greatriversnetwork.org/index.php?q=warren%20cadillac%20minneapolis&websites=no&historicgroup=all
2007 post searching for information on Warren Cadillac http://www.cadillaclasalleclub.org/forum/index.php?topic=97660.0
Thanks Ruel :<)