To Anyone, I pulled a boo-boo cutting my firewall back to install a US41 and somehow cut off my reference point. I hope none of you all do that sort of thing. Anyhow, can anyone give me the distance (dimension) from the main firewall to the front of the engine box firewall? No dimensions are in the book except the 6-1/2" required for firewall box fact to prop. line. Thanks, Ruben