Yeah the Pz III and Stug use the same lower hull, so it should be no problem. Get the Steel 3:1 gearboxes from RCCommand or the Asiatam 3:1 boxes from Phil at RCTankWars. He also has the mounting plate for the Asiatams as they use a slightly different mounting hole pattern. Either choice is a good one. One of these days i will be going this route with my PzIII but I will most likely use the Asiatam metal hull and suspension assembly. You should check those out, they are SWEEEEEET.