This is the threaded post with the round rubber bumper on either side of the cowl weatherstrip that supports the hood when it is closed. It is also used to adjust the closed height of the hood so that it sits level with the cowl panel. Sold individually, 2 required per vehicle.
Although it does not match the original, this height adjuster can be installed on 240Z's with no modification required. You will need to purchase the lock nut separately.