Part numbers on Johnson motors don't match their catalogures
The Johnson HC683LP-022 is a 12 V (max), ~20000 RPM, 338 W motor with diameter 35.8 mm, intended for electric drills. 



Johnson appear to make a very large variety of similar looking motors. Your best bet may be to search their site for the model that best matches the specification used in the advert of the ones you purchased and hope for the best.

Since the eBay listing has no information, you could measure and weigh them (without cog) when you receive them and compare with Johnson specs for various motors (they are sorted by casing diameter).

I'd then try them with lower voltages and monitor temperature.

There are disadvantages to buying from cheap eBay vendors.