Visit this site: http://carstereohelp.com/stereoremovalNis300zxFSpk.htm Scroll down to the 300ZX section. You should be good to go.
On my 93 the thermostat is behind the water pump. If you remove the waterpump you will see the thermostat.
To change PVC valve on a 1993 Nissan 300zx, first remove the oil dip stick and remove the tension clip from the PVC valve hose. Then remove the hose and the old PVC valve. Replace with a new PVC valve.
Inside the fuel tank. Some '93 and later models have an access hatch from inside the trunk; If not you'll have to drop the tank to reach it.
I believe that is in the trunk / hatch area , covered by an oval shaped rubber plug , at the rear near the tail lights
You have to remove the dash completetly in order to access the heater core...i did it on mine and it's a big job... took about 14 hours
Access through right side of trunk - remove panel and replace as complete unit
Open the trunk or hatch and pull away the interior panel/carpet stuff and just turn and pull out the socket and put the bulb out of that.
free
Undo the rivet under the lock, pop the black clip out and the lock slides out.
The short answer is "The car stops running" If your gauge is not working you have ot remove the tank and look in it. Sometimes there is an access hole in the trunk over the tank where the fuel pump assembly is. look in the trunk under the trunk mats, if no access you have to drop the tank
93