The frame is laid out in the book, and there is another person that published mods to make it twice as stiff, and even more stiffening mods done by Australians to meet their strict rukes. Also, the frame is not done. The 16ga metal floor and tranny tunnel add a lot of stiffness, as will the dash support. The frame plus those mods will be three times as stiff as the original, and weigh 160lbs.