...found out how the front seats were modified.
The hoops do indeed look like they came from an Amazon - see Amazon spares book. They seem to have been welded onto the PV lower seat rails. Access to the cross head screws is made via the holes in the tube (not sure if that´s how they are on the Amazon) =>
Nicely modified (in my humble opinion) as they´ve seam welded all along the two joining surfaces on both sides of the hoop - mega strong.
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I´m glad I ripped up the floor mats and removed the old sound insulation - water ingress was starting to take hold. I think I´ve caught it in the nick of time.
Finally finding evidence of the original body colour too!
That and the discovery of the stamped chassis number has removed all concern about inadvertently picking up a ringer of yore...
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In other news - reason for strangely aligned trim piece between front door and bonnet has been found =>
It was poorly put back together again with a screw instead of a proper clip!