I installed a 280zx 5speed in my late 73 240z with no problems. the shifter fit fine and so did my driveshaft. I so believe you need the later throwout bearing or the clutch won't work correctly. Also use the speedometer drive gear from your 4speed to keep your gauge accurate. I don't remember what year trans I used. There are 3 different kinds not including the turbo, and I don't own that car anymore. Hope this helps. PS My gas mileage did not really change. Still got about 28mpg on the highway in either 4 or 5th gear. It was quieter though.