The 660 shocks are 3/4 inch longer, that's it. I've had mine off both of the machines, and measured them. I say go for, that little bit of length isn't gonna matter much. And the balljoint argument is win/lose type of thing. One guy says they work fine without weakening them, while another says they'll break almost instantly. The only thing I can think would be this analogy: YFZ fronts on a 660. The difference is length is about 1.5 inches, yet you don't hear them arguing about balljoint failures. As soon as I get my hands on some YFZ fronts, my 660 shocks are going on the Warrior, no doubt about it.