I just came across this on the crane cams website: "The 318 arrived in 1967, and ran through 1986. These engines were often confused with the 318 ?Poly Head? engine. Cams were physically interchangeable, but the lobe layout was different for the LA. The 318 LA was also available in 2BBL and 4BBL versions." Are the cams really interchangeable? I thought the Poly cams were different from an LA motor? Bill M 65 Coronet 500 'vert