OnYx

does it still have the cam gear? The Z6 uses a solid front camgear and the Y8 uses a 5 "armed" gear.

sprocketcrx

a quick note to tell the diffrence and its a lot easier than any of this other stuff except for the cam gear thing. flip the head over and look at the area where the valves and spark plugs are. on a y8, the area outside of the valves will be square, making it more oval looking than round. the z6 head isnt squared off like that
http://www.geocities.com/bing_bong91...combustion.jpg
this is the y8, the combustion chamber is very similar to that of a gsr head as i understand it.