I have the early whale tail from my abandoned project available. This is a DIY tail, with a fiberglass tail bonded onto a factory steel decklid.
I was looking to emulate the RS 3.0 look, but didn't want to use an authentic early whale tail due to both expense and the fragile rubber lips. I decided I wanted an all-fiberglass unit (where the lip is fiberglass and not rubber), but the ones I saw all fit like crap and inevitably warped over time. So I decide to borrow an idea I saw on here and sourced a fiberglass reproduction of just the tail portion. I added flanges to all the mating surfaces (it was originally designed to be bolted to a plain decklid) and bonded it to a factory steel decklid which came from an 80s Carrera (using 3M panel adhesive). The resulting steel/fiberglass assembly is rock solid - the 3M product is amazing. It should fit really well, since it is based on the factory steel decklid frame - the same foundation as the high-end ducktails being produced today.
To complete the tail, the seams between the fiberglass and steel all need to be treated with filler and blended in to the surrounding areas.
I will also be providing fiberglass masking templates, if you want to paint a faux rubber lip using satin black paint. I made them using a fiberglass/rubber whale tail, so that I could paint the lip with the same lines as the factory part.
Asking $500 plus shipping. Or collected in San Diego. The GT Racing all-fiberglass tail is $840.