The main difference between the WS7 II or III and the S7II or now III is the crank shaft, they have the same piston/sleeve/rod. Slightly different carbs. Thw WS7 line also has the caoting on the crackshaft.
Josh's "Pit Guy"
Bones Brew Fuel Dealer
Thank you to his sponsors Mugen, J-Concepts, The Nitro Shop, Loosenuts Racing, Savage RC Motorsports, Ford Designs.net and FTR...