here is a pic of the frame section i built. it has the "z" shape easily visable. I also want you to see that where it meets the original frame work it slips over and sockets into the old stuff both at the rear and at the start of the angled piece where the outer frame supports slip over the new work. since my math skills are lacking i just kept grinding the pieces until the angles were correct. this was a pain as the angled piece in the pic is a compound angle. it rises up and inward to meet the crossmember see the next step and compare to this one.