Raw Step Headers Designed for: 62-79 B-Body, 70-74 E-Body, 76-80 F-Body And 77-78 M-Body With Small Block With Small Ports. * Please state at time of order if you have a 273-318 cylinder head with the port size 1.550 X 1.090. Primary tube size: 1-5/8″ O.D. Secondary tube size: 1-3/4″ O.D. Collector Size: 3″ With 3-bolt flange. Flanges: 3/8″ thick, laser-cut, contoured for a leak free fit.For more details visit the TTI Website.Price does not include shipping. FOB from Corona, CA 92880-1726 . Shipping can be very expensive depending on your location. For an accurate shipping rate please call us.