That is correct. I ended up getting a part from Greddy that was originally for the emange unit that was made for the 350z & G35. It's called GReddy e-manage RPM Signal Extraction Adapter #1 - #15900904. I needed to get an RPM signal for my Apexi SAFC to work properly. There is no wire that will give u a straight RPM reading. This the only I found out from nissan.The ECU doesnt recieve an RPM signal, rather, it recieves a crank angle signal. Most people install some kind of RPM adaptor in order to extract a single RPM signal.
What do you need the RPM signal for?