We missed a couple of pieces in that last photo. Here is the 3/4 x 1 1/4 mahagony piece that gets screwed to the floor to support the bottom of the 1/2 inch plywood back.

Qty 2 - 3/4 x 1/8 aluminum straps that have been bent and drilled. These are installed on top of the side blocks to hold and guide the rear pins.