What the £×€%$! Is this?

It's the antitheft stuff, I think?

The GLL models had the amp under the passenger seat

The antitheft box is located under the passenger seat. The amp is also located under the passenger (I think) on models that have it.

Yes that is the radio amp.

Some rusty, crusty crapola

So then is there not an obd in here somewhere?

The ecu's in z31s do have diagnostic codes you can lookup. I believe the ECU flashes lights to represent codes. Read more here http://xenonzcar.com/z31/ECUcodes.html

But where is it? I thought under the passenger seat?

Passenger side kick panel. Behind the plastic trim piece under the glove box on the side of the body. Have you checked the FSM and XenonZcar?

Ya ya. Ive got the fsm right here. Im gonna see if i get a code off the com

You're probably referring to the standardized OBD-II plug that is found on all late model vehicles. The Z31 predates this common standard.

Yeah. The 96 300zx is the only 300zx with OBD-II. Vehicles before 1996, so any z31, does not have OBD-II