Hey thanks for the info. The C5 intake is indeed the 2X4 lowriser. As for the block, I might just go to the local machine shop and have them take a look since the block has two sleeved bores. Are there any other number to look for in the heads that might help me further identify them? I ask cause someone else told me in another forum that they are junk and should get rid of them because there intake port was too large. Dosen't make sense. I really appreciate the input. Thanks abunch.