OK ... two separate references list the first long branch manifolds coming out in 1963. They remained relatively unchanged through 1969. They were used more extensively in production cars starting in 1965, being a dealer option or parts-counter product until that time.
Today, there are the orignals, and there are reproducitons. The reproductions come from at least three companies, and the "better" ones come from R.A.R.E. and are available in two styles: Standard reproduction (2.3" collector) and a larger 3" collector version. These are almost out on the market. Other reproductions have been available for some time.
