I own 3 Powells & host the Powell club on Facebook. There is also a Powell Registry if you look on line. Your serial number is stamped on top of the right frame rail below the area of the manifolds. All begin with PMC and 4 digits after that. The seat bottom is just a foam block with vinyl, and the back is a board with foam & vinyl along with 2 6" long pieces of 1/8" x 1" tall strips for your seat adjustment. I can send you dimensions. These are super easy to restore, most parts are from something else. - Miles PMC-2083, PMC-2172, PMC-2934 http://clubs.hemmings.com/powellregistry/index.html