I have two keys for my 300D, one is the original plastic headed key, the other is a one with a head that's part of the key, sort of like the Ford and GM keys from the 70's and 80's.
-Joe

__________________
'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.