Just throwing this out there, maybe something you havn't thought of yet, but demolishers tires make a great neck. Simply unscrew them, and push them together with a homemade pin. (I made my pin out of an allen key) I just set the wheels on the rest of the body there, but they could easily be attatched properly, and a ball joint used on the two wheel pieces to make them posable. I may even pick up a few more loose constructicons to eventually build a figure of my own, but I just thought I would post this anyways incase anyone else wanted to try. I thought it looked pretty neat.