These models were available in three different permutations ("original", "modern" and "final rebuild").
The engine chassis is metal and fairly minimalistic (with most of the actual heft provided by the brass shell). The motor is an open-sided, straight-wound five-poler. Right-rail pickup is provided by the pilot truck, the trailng truck and two of the three right-side drivers (the front pair of drivers being equipped with traction tires). Left-rail pickup is provided by all of the left-side tender wheels. Current is transferred from the tender to the engine by way of a stiff wire on the drawbar (although in the above picture, an insulated mini-wire has been added for more reliable conductivity). Only the middle pair of drivers is geared. The driveshaft/flywheel/worm assembly turns a plastic idler gear, which then turns a brass axle gear. The pilot is equipped with a non-operational knuckle coupler. There is no coupler on the tender, although space is provided for installing a Micro-Trains coupler on the tender chassis. Wheels are low-profile, so no problems on Code-55 rails. There is no headlight.
This was my first brass steam locomotive, and I have to say it's really quite amazing. The details are breathtaking and the performance is stunning. It runs every bit as smooth as a Kato Mikado, with sensational slow speed performance and a very reasonable (I would dare say prototypical) top-end speed. OK, it's not quite as whisper-quiet as a Kato Mike, but it's not what I would call loud either. I guess one concern is the fact that the worm is free-floating, which could lead to some noise/vibration when pulling a heavy load. And then of course, you have the whole "stiff-wire-on-drawbar" situation - often a prescription for iffy running (although the flywheel probably goes a long way towards smoothing out the occasional loss of tender current). Minor caveats aside though, this is just one great looking and running steamer.
Here's the "final rebuild" version -
And here's the "modern" version -