I own an early 1977 280z - the one with the sloped rear deck. I wanted to drop the rear cargo deck to make more space in the back. I have found a thinner replacement spare to fit the shallower area. I also plan on removing the braces that are welded to the floor that hold the rear deck up along with the long brace that stretches the width of the car at the front edge (by the seats) of the rear deck. Next I was planning to buy some 1/4inch or 1/2 inch MDF and create a new floor to compensate