So I was doing some digging, and I think its supposed to be one of these:
http://pwencycl.kgbudge.com/2/t/2TM_class.htm
I can't find a photo of one of those, but it looks very much like it's a downscaled version of this:
http://pwencycl.kgbudge.com/1/t/1TL_class.htm