Thanks vstech, this is the first time I put pictures up on PP, so it it's worth ezplaining that the two pics at the end of the post are views of the two styles of vibration damper I have on hand. In both pics the one on the left came off my !982 US turbo 300D, on the right is the one from my 1984 Euro spec non-turbo 300D.

The ebay link is to a vibration damper (harmomic balancer in ebay listing) from a 1981 or earlier non turbo 617 motor.