I'll confirm that as well. The spur gears fit inside the cup gears in an Alco PA1. Sekeisku? I think that's how you spell it.
Those are first-rate five-pole motors, seriously. I repowered my Model Power RSD15's with those back in the 80's and they are still running today, smoothly, with the same motors. Quiet, powerful, and cool and narrow enough to fit in a hood unit. I also did ... hmmmm.... maybe five Atlas GP7's (Roco, ones with the red plastic gears) with those motors for other friends and they are still running as well. They wore out contacts and gears but the motors are still just fine.
At the time, that was absolutely the best five-pole motor out there and I'd still put it right up there with any Kato motor today. Other than the fact it's not skewed, it was way ahead of its time.