Found them at O'Reilly Autoparts, Dorman part #961-375. Both 1/2 inch and 5/8 inch, total of 6 bumpers. Had to find them myself, salesman didn't know where they were.

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Joe Myers

'83 300D (light blue)
'82 300TD (off white - parked)
'87 300SDL (silver)

'75 300D (black - sold)
'76 300D (beige - totaled by pizza delivery car)
'82 300D (metalic blue) sold