I think that most of us are inflicted with "catalogitis", a highly infectious ailment that we are subjected to at least twice a year. This disease manifests itself when we are compelled to ravage through the new catalogs and we have virtually no resistance to purchasing new engines appearing in the wonderful pages. One of the symptoms is to experience temporary memory lose of our current inventory of engines. This is highly dangerous as this causes acquisition of engines without any concern in terms of what we have in inventory.
So I now know what I have! I do not have a area for a display, so any engine is more then enough for me. Just today I was surprised when I received a Lionel SP SD40T-2 engine by FedEx which was in Lionel's 2012 Vol. 2 catalog. And this was the first additional engine that I bought to go with a set. It maybe the fact that I have the first TankTrain set which came with 2 powered engines.
Or the fact that I also ordered the N & W Pocahontas set, when I already have N & W J-class engine but I wanted the passenger cars to go with it. For some reason I did not order a NYC Mohawk engine, and I do not have one. I did put in a order a CN Piggyback set after Lionel cancelled the Acela set. So apparently the catalogs do have an affect on me. Maybe I should stop looking at the Lionel catalogs or maybe that is why I don't look at other manufactures catalogs. LOL