As you can tell from my Avatar, my favorite railroad is in the 'other' category, LOL! However, you did mention Southern Pacific, which is my SECOND favorite railroad (and one I also model), so I was able to fit in somewhere. Of course, I also have 'borrowed' power from Colorado & Southern, Chesapeake & Ohio, Pennsy and Great Northern, so I suppose you could say that almost everything I model is in the 'Other' category. But hey, that's what makes this such a fun hobby, right?
Tom