I just put whal bros on mine and from the moment I pressed them on the shaft, I knew they were trouble. Even with the arrows lined up, the teeth weren't aligned properly and have caused a horrible vibration in my sled. It's not as bad now with 2 rides, but it sucks that they need to break in rather than being good out of the box. My shaft on was 1 1/16". As for the doo drivers, they are FAR superior in my eyes and unfortunately are only available with the shaft. Or at least that's what 2 doo dealers told me in BC.