I have never seen the Pittman 700 series referred to as sidewinders. But they fit the bill in slot car applications. I
was using that motor for model railroading as well, most notably to power a Lee Town Climax. It was perfect for
use as the center drive shaft on that model. But I never had one with plastic gears.
Only the first one, the 703, had the plastic gear. Not surprisingly, in slot car applications, the gear routinely lost its grip on the axle. The solution was to cross-drill the hub and axle (fortunately not hardened steel) and pin them together.