If you cannot locate factory reference or depiction, contact Gardner Exhaust, Long Island, N.Y. From what I was advised by owner when ordering a set for my 69 Biscayne, they had pattern system from Donny B. I had requested 2.5 inch set of piping which Gardner fabricated which fit as perfect as you can hope for! As you may know the L-72 equipped cars had tail pipes exit from behind rear wheels.