the 600 series is the 2004.5 325hp. the 305hp is the HO pre-new fangled smog stuff in the 600/610.. i would prefer a 305 but its not a 600 series. 600 series are 325hp. i don't think there is a 305hp/600 series.Tinman875 said:He told me a 305hp/600 series. what were they for sure???