How do you identify Honda ZC heads?

There are both SOHC and DOHC ZC engines. The non-VTEC SOHC ZC is similar to the D16A6 ('91 - '96) and D16Y4 ('96-2000) engine, but with more aggressive cam timing.

The DOHC ZC is similar to the D16A1, D16A3, D16A8, D16A9 and D16Z5 engines. there are two DOHC heads "brown top" and "black top" which comes form the color of the valve cover. the brown top has the valve cover studs located in the center, over the cams. were the black top has them around the edges of the valve cover. not on the top/center. the heads them selves are the same and interchangeable and you can also use a 88-89 integra d16a1 head. however the ZC has more aggressive cams then the D16A1 does.