Yep Denny has it pretty much covered. And man that sounds like a great deal!!!! Hope you got em. They are really good heads and can support up to 400 HP in stock trim. Anything above would need bigger valves and some serious port work. They are pretty much the exact same as the C8AE-H heads only the D2's have the hardened seats as Denny mentioned which is a major plus. Chambers are 68-71 cc's but found them closer to the 68 side. They have the typical lowered exaust port of the 67 and later heads. Nice score!!!!! G.