Aftermarket head question

[blshoe]

I just tore my engine down because of a cracked block, I cant find a GM part number on the heads, Im wondering if the heads were the updated aftermarket version, the only ID I could find was stamped on the exhaust face ; MD1203.
Any help would be appreciated

[Robyn]

You can find the casting number as well as GM under the Valve cover.

The part number will not usually be stamped on the head.

The aftermarket heads may have a casting number or may not depending on who made them.

Best

Robyn