DaveC:

If memory serves Ferry Porsche's 73 2.7 RS was sans ducktail, light green metallic, and debadged per his request.Two other family RS were sportomatic.  Porsche understands that customers want different flavors and are willing to pay for the privilege.   

The 73' 2.7 RS could be specified with the rear ducktail delete option, it was a factory option available to all customers. In my opinion there is nothing wrong with Porsche offering this option on the GT3. 

rsducktaildelete.jpg