These are extremely nice locomotives, and definitely superior to Endo's SD-XX diesel models (also imported by Key) released around the same time. The looks are tremendous, with nice features like working headlights, window glazing, non-molded handgrabs and see-through screens. The mechanism is simple and solid- the entire chassis is a current-moving PC board (no wires anywhere), and all of the gears and driveshafts are plastic (as opposed to noisy metal). All wheels provide pickup (or at least they can, but more on that in a moment). The motor is a 5-poler. Both units (A and B) are powered.
Performance is top-notch, but with one caveat. As delivered from the factory, these models come with one traction tire per truck. And as such, they run good but not great. Slow speed performance is tremendous and they run nice and quiet. However, pickup is a problem (particularly through turnouts). Eliminating 25% of the footprint on a four axle diesel just isn't a very good idea. And as is generally the case with traction tires, a certain amount of wobble and wheel noise is inevitable. The good news is that a couple of easily installed non-traction tire wheelsets are included in the box. Once I replaced all the traction tires on my units, performance immediately jumped up to modern Kato/Atlas levels. Not surprisingly, I recommend the change.
One potential issue with these models (as they age) is the fact that over time the plastic driveshaft U-joints have a tendancy to loosen up and start slipping (thus causing the locomotive to lose power). One solution to the problem (should it occur) would be to replace the U-joints with plastic sleeves. EG -
As delivered, these models come with a very strange coupler situation. The forward truck on the "A" unit does not have a coupler attached to it. Rather, a non-operating knuckle coupler is jammed into the small hole in the pilot (IE, in the shell) and held in place with a wire. I think it's just there for looks, as I seriously doubt you could reliably couple anything to it. Said forward truck does have a coupler pocket, but I'm not sure what exactly you might be able to attach to it (given the extremely small hole provided in the pilot). The rear truck on the A unit and the forward truck on the B unit have similar knuckle couplers, although these are actually mounted to the trucks. They make for some extremely close-coupling and don't appear to interfere with performance (I can easily run mine around on 9.75" radius curves). Lastly, the rear coupler on the B unit is a truck-mounted Rapido-style coupler. There is (or at least, was) a Micro-Trains coupler conversion option available for this particular coupler. I'm not sure if this specific MT conversion is still available, but I imagine the clever modeler will be able to find something that will work.
Popping the shell on these models is pretty easy. Simply remove the four screws (two on each end) holding the shell to the chassis (no need to unscrew the fuel tank). This will also free up the pilot (a separate part) on the A unit.
Grade: A (without the traction tires)