Below are a photo comparision of the WBB [Formerly K-line] Rs3 vs. The 2003-2004 Weaver Rs3 w/Dual motors:
For Diesel detailers/ bashers, one this is for sure, the Weaver models are easier to take apart than the WBB models and if you want to model the "long tank" RS3 version, the Weaver models fuel tank is easier to cut while preserving the interior tank speaker mounts for sound.