Well, got my old Hooker competition headers out. Number stamped on the flange says L9900 7 91. These are 2 inch adjustable from my 63 Max Wedge car. Bought in 91, run 2 years and car was parked in 93. Can't seem to make any sense of that number. My guess it will fit old B body with an rb block (413, 426, 440). Maybe someone knows more than me.