The rewiring of a tank is not too bad. It is all about understanding each electical motor in use needs to have a positve and a ground supply. On the RX 18 the ground supply is switched through the RX 18.
The best thing to do is gut all the wires and then just sytematically start hooking them up back to the RX 18.
A detailed pinout diagram of the RX 18 exists here
http://battlearmorrc.weebly.com/uplo...00047_orig.jpg