Speedo and reverse lights

[7MGFORCE]

Installing a t5 an down to two things.

 

Speedometer hook up confirmation.

Based on what I read through search and emails I can buy jtr speedo (dat 111) and I will be able to keep my stock speedo.

 

My car needs 20t gears and I found one on eBay with clips.

 

Are those the only thing I need to hook up? Or do I need something else?

 

 

The other is reverse lights. While it's not a must it sure would be nice. If I'm correct the reverse light switch on the t5 is the black thing with two prong sticking out on the driver side of the t5 correct around the middle area.

 

Now the 260z has four wires. Anybody know why is has 4 wirescoming out of the engine harness and wich is for reverse light?

 

Thanks