Z's had an optional 3.23 gear. A simple way to check gear ratio is to jack up the car, put it in neutral, mark the drive shaft and tire with a piece of tape, rotate the tire one revolution and count how revolutions the drive shaft turns. If the DS rotates about 3 1/4 times you have a 3.23. If it goes 3 3/4 revolutons you have 3.73's....etc.