I have a 81 F250 reg cab with a 351m. I am building a mud truck out of it.. I started it up the other day a noticed that the passengers side manifold was cracked and fire was passing threw when reved up. I think im just gunna take the manifolds off and replace them with headers. Im wondering what is a good type of header for these engines? i was looking at hooker compitition headers and they seem like a good buy for around 250 with bolts and gaskets. Also wondering if they bolt right up and fit good or do you need to hack and cut into anything? thanks..