A 300CD windshield will not fit a 300D, they have different part numbers. Also, if you look at a 300CD and 300D side by side, you can see they're different.

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'81 MB 300SD, '82 MB 300D Turbo (sold/RIP), '04 Lincoln Town Car Ultimate

Sooner or later every car falls apart, ours does it later!
-German Narrator in a MB Promotion Film about the then brand new W123.