MY15 shark fin diagram here - the top where it saw ZN6 A,B are for original cars while the below diagram where it says ZN6 C is for the MY15 car. Part numbers are included although as you will see if you read further the part numbers may vary from country to country
As mentioned it replaces the whole antenna assembly so looks like you need to remove roof liner to get to bolt that holds it. As this part is the antenna assembly and amplifier it is very expensive.
Part number here in New Zealand is SU003-05515 for the shark fin and base. You will see the diagram part numbers for the base are the same so you'd need to be sure you're ordering the new version "C" rather than version "A, B".
The wiring has different part numbers from the MY14 and earlier models with three parts being SU003-02659, SU003-02661 and SU003-02658 while the MY15 shark fin has the part numbers for the three wiring sections as SU003-05230, SU003-05232 and SU003-05229
Your part numbers may vary.
Personally I have tried four shark fins being beatsonic, modellista, a cheap ebay one and the genuine TRD fin. All degrade the FM reception.
The TRD one (even though I have full TRD car) is ugly as sin. Far too big and is more an entire shark rather than just the fin! The beatsonic is nice but I think the modellista is the nicest I have tried. I am now using internet radio so don't care about reception so have the modellista one back on - it's here
https://www.japanparts.com/parts/detail/41005
I have seen the 2015 fin in the flesh and it looks nice. Personally I prefer the shape of the modellista more but as it still needs to fit over the standard antenna base the MY15 one is smaller.
Pics of MY2015 fin I saw here
