Do you want the type that have the motor attached to each axle, or the standard solid axle that uses driveshafts from a center transmission with one motor...or does it matter at all?
If it doesn't matter, you can get the Tamiya Clod Buster, TXT-1, TLT-1, XTM X-Crawler, RedCat RockSlide, Custom-Built Solid-Axle Truck from
RC4WD.com, Custom-Built Solid-Axle E-Maxx (many examples & how-toes, like on
RCCrawler.com), or one of the many others (
Google)...