3 hours ago, Captain Obvious said:

Wow. That's a lot of complexity for NVH. Are you sure it doesn't have anything to do with something more complicated than that? Reverse interlock or something?

Thinking back a long time ago. Diahatsu Rocky transmissions had something similar in a couple of their transmissions. It was to eliminate rattles in the worn busses. The spring would always create tension on the bus/pin. That way it would not chatter when the diesel engine went through certain revs.

This could be Nissans solution to that. Could be.

It is not mentioned in anymanual and all the 280ZX parts list don't seem to show it either.

It just seems like a lot of trouble for a little bit of vibration. Not saying that's not it, but just that it's a lot of trouble for something they lived with just fine for the first nine years.

So any time you change gears from forward to back (like from 3 to 4, geometry says the vertical distance between the center of the pivot pin and the bottom of the plastic nub on the lower end of the shifter shaft changes. What is it that accounts for that? Is the hole the plastic nub fits into extra deep? Deeper than it needs to be to account for that?

Not sure I'm explaining that well without pics.

I've replaced my bushings, but that's as far as I've had to go into the transmission. Thankfully.

I’ve had a 5 sp “B” trans that had a lovely whine in 3rd and 5th that magically silenced when I did nothing other than change the shift knob to a much heavier version. Changed the harmonics of the thing completely. 

Checking that part number in the nissan part catalog. It comes up available, but they use the old 280Z diagram to show it. Makes it a little confusing.

Sure does, Courtesy Nissan gave me that as an option and when I looked I thought the same thing.