Project CRXtacy

ok, im at a loss again, i got some z6 bolts from a buddy (he says they are z6 bolts anyways but i dont believe it) i stuck em on and they are like 1/2" too long, what the ----?! i looked at the y5 head and the bolts mount alot higher than the z6 head so the y5 studs would be longer; right ? right. so does anyone know if i was just given the wrong bolts or what?! im at a loss. PLEASE HMT HELP!