Lou, I believe the only gas cap supplied on the W113 was the chrome, locking version. Most others are aftermarket replacements.
Since gas filler necks are kind of standard, it is pretty easy to buy a cheap gas cap at any auto parts store, some for just a few dollars. The OEM chrome MB unit is quite costly, and relative to say, the Stant, probably always has been. Imagine if, in 1972, you lost your nice gas cap, and went to the dealer to replace it. Maybe it cost $24.99; when a Stant at that time might have been $1.49, it's easy to see why many that went missing were never replaced.
The one you sent pictures of is probably some locking aftermarket cap. Ventilado, as if you didn't know, means ventilated.
I've seen some Alfa caps and they are every bit as beautiful as our MB cap.
The OEM gas caps are pretty expensive today, several hundred dollars. There are quite a few on eBay at the moment. Some are not OEM (w/o the star) but look pretty close. Others are OEM and more than twice the price. I think you can get them still from the Classic Center, too.
