The seat belts on early cars (fixed heads) were mounted differently to the later cars.
AFAIK all DHCs had the later style belts, with a metal runner for the belt to feed through secured by the mounting bolt on the rear deck. Maybe someone has fitted a different belt to your car in the past to replace a defective one?
Tony
<font size="1">1981 2L FHC Cavalry Blue
1980 3.5L V8 DHC Jaguar Regency Red</font id="size1">