While reading through the consists on canadasouthern.com, I found that Bay Terminal tank cars (reporting mark BT) were apparently sometimes seen in NYC trains on the Toledo and Lake Divisions and were routed at least as far west as Minneapolis and at least as far east as Pittsburgh. So modeling one is of some interest.
The question is, what were they? I can't find any record of the types of tank cars BT used during the transition era (although they apparently owned 325 in 1950s). The closest resource I've been able to find is a 1917 document in which BT uses a variety of tank cars owned by different companies.