Thats what I've been thinking....If you look at some of the different shocks, on different bikes, I don't see a big difference in how they mount...Maybe alittle stiffer but I don't think the frames are that much different. I think the 300ex and 400ex are pretty close, just different size motors...I've looked at the 400ex, looks just like a 300ex.....I'm gonna give it a try...Thanks for the advice..I think alot of it is the shock manufactures don't want you to swap out, they would rather have you spend 800 bucks on some wazu shock......If it don't fit, force it....LOL