I've got the printed parts guide for W114/W115 chassis. It shows one rear door for all four door models, left and right. So you should be able to use that later door.

I used a front drivers' door from a '76 when repairing my '73 without a problem. Just had to drill holes for the earlier style side view mirror. Vent glass and everything bolted right in.

EDIT: My parts guide is for W115 only. "Chassis and Body Spare Part List", printed July '73. It's good through the '74 body updates. I see no reason a later door won't work on your car, especially after my experience with the '76 front door on my '73.

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- Greg -
1973 220D, The Prodigal Benz
1974 240D