Made an upgrade of the 9398 with XL motors and gave it 30% more additional parts. This is my MK2 version as my first upgrade was not as successful. Also it uses
Lego Technic 42070 vs 9398 vs 42099 Which is the best Crawler?? - YouTube
LEGO instruction for set 9398 - 4 x 4 Crawler at BrickScout
Amazon.com: LEGO Technic 9398 Rock Crawler : Toys & Games
LEGO Technic All-Terrain Vehicle 42139, 6-Wheeled Off Roader Model Truck Toy, ATV Construction Set, Birthday Gift Idea for Kids, Boys and Girls - Walmart.com