The numbering of Tamtech Gear chassis includes several families; the 57xxx is the only chassis that needs to be assembled, while all other chassis are already factory-assembled (RTR - Ready to Race) marked as "*". Some models have been released both as assembly kits and as factory-assembled versions. Some models differ only in body color and decals. Special models released in limited editions and/or sold only in certain countries belong to the 84xxx family.