Loyal reader Justin Chan just sent through his conversion of the LEGO Technic 8421 model 2. He's done an excellent job and by the looks of it has crammed a lot in such a tiny space. It still has all the original functions of driving, steering, rotating / lifting/ extending the boom arm and even lowering the ground supports.
Looks likes he's got the Mindsensors Motor Mux to get all 6 motors to talk to the 1 NXT onboard.
The whole thing is controlled by another NXT connected via bluetooth.
All this from a secondary school student. Well done Justin!