Raw Step Headers. Designed for: 67-76 A-body, 62-74 B-body and 70-74 E-body With Big Block. rimary tube size: 2-1/8″ O.D. Secondary tube size: 2-1/4″.Collector Size: 4″ 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.