The body is made from the re-worked old Marx 333 mold. It is equipped with a can motor, traction tires and a decent gear ratio, so it runs well, pulls a lot of cars. It has no flywheel, so it stops on a scale size dime.
The cap on the stack tells me that it has the later smoke unit, which was even more anemic than the original Seuthe unit.
The tender is around the same size as the ones used by the K-Line semi-scale Pacifics and I think it was a new mold for K-Line. In my opinion, both that tender and the 1829-style tender that K-Line originally issued with these locos are too big for the loco, but that's just my opinion.
Here's an earlier issue with the tender Marx designed for the 1829
http://www.ebay.com/itm/K-Line...d:g:gm8AAOSw0kNXg5L2