Thats because Acme and Smartech (owned by the same people) use specs off other brands. A guy at my lhs runs Smartech and has every part figured out.. if he breaks something he has a little chart that says "HPI xxx" or "Traxxas xxx" that tells him what part, from what brand and car will work. Took awhile to figure it all out, but it works. Some of those offbrands are shipping with Trinity engines now, worth checking out. But like everyone else said, its going to be a pain in the BUTT finding replacement parts made by that company.. unless you plan on ordering.. and even then its hard.