correct ex mainfolds for my M code 69 440 dart?

I just found my old exhaust from an M code Dart that I used to own. The number on it is 2846729 and has the bend near the flange to go around the steering. Looks like the piece I have may not be the original type exhaust for an M code car. Now I'm wondering what this piece really is...................it was a perfect fit with a 440 in the M code as well as my 68 convertible Dart.