While the body of the mirror is pretty much the same for the coupe, the base (the part that connects to the door) is shaped differently because the coupe's windshield angle is different when compared to the sedan or wagon. A sedan or wagon mirror will not fit. But some parts are interchangeable. Maybe you could take a sedan mirror, disassemble it, and use only the parts you need.

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Dale
'67 Volvo 122
'79 Rabbit Diesel
'79 M-B 300TD
'82 M-B 300D
'83 M-B 300CD
'85 M-B 300TD
'86 Isuzu P'up TD
and a couple of Hondas