My W115 1976 300D (135,000 miles) started nailing badly so I decided to replace the original (as far as I know) injectors.

When I removed the old injectors I did NOT find any heat shields.

When I look into the threaded receptacle for an injector I see a 3/8" (or so) hole in the sloped bottom of the receptacle but no heat shield. The new heat shields that came with the rebuilds do not look like what I see at the bottom of the injector receptacle.

Is the bottom of the threaded receptacle actually the heat shield, and I'm not distinguighing the bottom of the receptacle from the heat shield?

I'd hate to start tearing up the bottom of the injector receptacle thinking it was a heat shield when someone failed to reinstall the heat shields as some earlier time (however, I have all the repair records for the car and none suggest any work on or involving the injectors).

Did the W115 76 300D come with injector heat shields?

Would it be better to install the new heat shields regardless?

Robert