The SY's were released in late 2003, months after the proposed release date - which seems to have become a continuing trend from Bachmann! There has only been one production run to date with 4 versions, two Chinese and two US, in what appears to have been a bit of an ultimately failed probe into the US market, given that it took a very long time for them to sell out there. I think many of the US versions were retrofitted with decoders to improve sales some time in 2008. The Chinese versions sold a little quicker, but certainly far longer than the QJ's ever took.
The SY's are very highly detailed models with hundreds of seperately applied parts in plastic and brass. The lettering and lining is very nice, although I find the 'red' areas to be very orange (wheels/pilots). The main flaw I can find is that there is no all-weather cab, unlike the real SY's which are completely enclosed with cab doors and flexible cover between the cab and the tender. On the model, there is a corridor section mounted to the tender which leads to nowhere and is probably designed this way owing to the complexity of the drawbar system, however if the QJ's and SY's can do it...
The SY's are highly responsive machines with a very slow starting speed and a top end speed that would rival the Shanghai airport Maglev train (outrageously quick). The motor is most likely geared so high in order to compensate for it's very light weight. Unfortunately being such a small engine, it's hard to imagine where any extra weight over the drivers could have gone without making the main body shell metal instead of plastic. On level trackage, the model should capably haul 10 - 15 freight cars, on even a 1% grade, this drops dramatically. On the 3% grade, it will haul perhaps 2 or 3 before the wheels start slipping.
Wheel pick up comes from the tender axles and the driving wheels on the locomotive. Current is fed to the circuit board in the tender, which is fed back to the motor and headlight in the locomotive via wires. The board in the tender has an 8 pin plug for a decoder, however disassembling said tender is a pretty complex proceedure. The LED's on the US versions have a very yellow hue, which looks nothing like a real headlight, but is better than the two Chinese models which have a bizarre orange/green color.
The SY's can take Kadee #5/#58/#158's (or #53/153 for close coupling) on the front, and an NEM style Kadee #17 on the rear.
A very nice looking steam locomotive with some very poor performace qualities.