Possibly they were used there as well but who knows.
I have a single fuel line so I doubt my car was one of those. Too early for ZL-1, not on the list, DG3 on the rear seat bulkhead. Original chabered exhaust car. Hard to say what it was originally with any certainty. The possibilities are mind boggling. I had to just believe the DG-3 crayon mark and run with it. I will keep the car and the springs indefinately just in case better info comes along some day.