My understanding is that the 127.980 engine was for 58-59 220SE sedan. The 127.984 is for the 59-60 ponton 220SE coupes/converts, and also the 60-65 W111 coupes/converts. My question is what is the difference between these engines? Will one swap perfectly for the other with no mounting or auxillary system modifications? Specifically, can a .980 (sedan) engine be put into a 60 220SE convertible straightaway? Thank you very much for any help and details you can give me on this. Jim