made from 66 to the ones made in 73 and 74 just before the integral manifold came out? Its seems that something was changed during the 73/74 years from the earlier ones. Want to put one in my full size mid 80s pick up but need to know what the difference is. Thinking of going with a balanced 250 and a mild cam, modest headwork and roller rockers and a small 4bbl. Would a 470 cfm truck Avenger be too large or do I need a 390 cfm? Thanks. Henry
