Tony is correct; large 930 tail was available as an option on SCs in '82 and '83. Not sure about previous years, but Weissach edition certainly had early turbo-tail w/ one grille from factory, and SC/RS(?) had duck-tail.
As for aesthetic value, it really depends on the car, IMO. Right spoiler depending on color, wheels, etc. All subjective of course. I like the duck-tail on Jack Olsen's car a lot. I had a freind w/ a new '83 SC cab back in '84, grey market ROW car w/ turbo-tail from factory, triple-black w/ cool stickers in french on windshield, one of my all-time favorite 911's.
