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
1 x Lego Technic Model Set 9398 4x4 Crawler Electric Motor 9V Power Functions L Grey Red Tested with BA Incomplete Incomplete: Amazon.de: Toys
LEGO Technic 9398 Rock Crawler by LEGO Technic : Amazon.co.uk: Outlet
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LEGO 9398 4x4 Crawler – 2TTOYS
REVIEW] 9398 - Rock Crawler - LEGO Technic, Mindstorms, Model Team and Scale Modeling - Eurobricks Forums