On the bottom of my 03 g35 coupe, I have 3 pigtails. I know two of them are for the downstream 02 sensor. But there is one more pigtail that I'm trying to figure out where it connects. Thats basically what the pigtail looks like. It's attached to the downstream 02 sensor pigtail.

 

2 upstream O2 sensors in the headers
2 downstream O2 sensors in the catalytic converters
1 crank position sensor at the bottom left of the bellhousing

Also, 6MT cars have 1 PNP switch and 1 reverse switch mounted on opposite sides of the transmission towards the rear of it.

 

Thank you