We just put a set on a 408 and had nothing but problems. Thought we had head gasket issues and come to find out it was a bad casting in the water jacket. After having this problem and doing some researech on them. There was a comment that if there was not a market for CHEAP parts we would not be in bussiness. That should tell you something. We are trying to get pro comp to help with this issue and will post later on the out come.