ATS 3 piece mainfold
 

will a 24 valve fit on my 12 valve head? my buddy has one he wants to sell and its a pretty good price.

i think not, the ports might be a diff shape but im not 100% on that

It'll work but you need to customize gaskets the 24v are oval and the 12v's are squared you'll be better off getting the 12v manifold

Yeah thats what i was going to say is the difference. You might be able to have a machine shop machine it out for you, but by the time you get that done, you would probably have been better off to buy a new one specifically for the 12 valve. Not only that I dont think you could machine it enough to match the ports up properly without having it cause reliability issues, such as cracking the manifold. That would be my hypothesis.