Speaking of unknown tank cars.... I got one of these for Christmas:
http://pictures1.kyozou.com/pictures/_18/17335/17334167.jpg

LOL..... it's part of the Walthers Trainline, but it resembles the old Athearn car. Most of Walthers Trainline is inherited tooling from Train Miniature, Life-Like and others, but I don't remember anybody but Athearn (and possibly Mantua) making a car this large... Athearn also made a 3-dome car of similar configuration. I figure it's bogus anyway, but more curious as to where the tooling came from. Varney's old tank car was smaller (and I think more prototypical). I doubt Walthers would have tooled up a copy of Athearn's car, so it had to come from somebody's old tool bin, but I'm just drawing a blank. Walthers had gotten a lot of mileage out of this mold, they even did it as a "fire fighter" tank car...

Andy