Passenger seats of this period folded forward to lie flat on the base cover, which in turn allowed the entire seat to be folded forward for easy access to the rear. The seat squab cover is shorter than for fixed seats and fits slightly differently.
Fitting the seat covers, seat straps and foam/fibre paddings will be same throughout this period. Basically, the Pirelli straps hook 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. During this period, the drivers seat was a fixed type, whereas the passenger folded to give better access to the rear seats.We would suggest that you strip one seat first to see exactly how it is fitted, then assemble the straps and foams etc and the fit the covers in a "dry" run before final fitment.