The squab cover is the piece you lean against. This design has simulated stitch lines that we press into the vinyl with our High Frequency welding machine. This is the original Factory design.From 1960 until the mid 1970's all non reclining front seat frames were the same. Fitting the seat covers seat diaphragms and foam/fibre paddings will be same throughout this period. Basically the diaphragms come with hooks to clip onto the frame the squab padding kit and base foam pad are glued to the frame. The seat covers once fitted are held to the frame with metal clips. We would suggest that you strip one seat first to see exactly how it is fitted then assemble the diaphragms and foams etc and then fit the covers in a dry run before final fitment.
Newton Commercial Part No - SC3042