Which (units) are you talking about? If it is the gear boxes that you mean, NO, everything you are seeing on these tanks are custom builds. The stock power train and radio gear are very cheap toy grade stuff. They are in no way even close to hobby grade straight from the box. Actually they don't even come close too Heng Long quality as far as those aspects go. Thesetanks have great potential, but do REQUIRE a lot of custom work to get them to be good runners. Now for some one who just wants a really cool toy, they are fine OTB.