Just did a bunch of reading about how gear module/pitch is determined and defined. It boggles the mind that some crazed loony (effin engineers, eh?) sat down and figured out a more difficult way to express a simple idea, then everyone went along with it.

Equally as difficult to understand is why Tamiya and a few others, chose to run with .6 module, but only in part of their product lines. It's mostly used in cheaper products. It would seem running with the industry standard would be more cost effective, but I suppose this is just a different industry standard.

As far as who makes/uses .6 gears I've found Tamiya, Duratrax, Redcat, Kawada, Yeah Racing and several industrial suppliers. Always go with hardened aluminum, Duralumin or steel. And never, ever, use the pinion Tamiya puts in the kit, unless you're just starting out. Good pinions are cheap. Crappy ones are cheap too, but they wear out quickly and take the spur gear with them, then you're buying more than you need to.