Help identifying ball lock keg

[szap]

I recently acquired an older ball lock keg. In checking it out, I found that the lid is different than any I have seen and is smaller than the ball lock kegs I have. I have posted pictures. Can anyone tell me what type of keg this is. I hope to be able to get replacement O rings for the lid

 

[Whisky River]

I can’t help identify your keg but I would be interested to see the differences between the lid you have and a “regular” lid. Is your lid made of plastic? Can you post a picture of the green lid next to a regular metal lid?
Thanks

 

[szap]

Here are the photos. The lid in question is made from some type of plastic or hard rubber. It is not metal. The one picture is a side view and shows that the lip the o ring sits on is thinner on the metal lid. Hopefully you can tell the metal lid is just slightly larger. Not much but enough that the lids are not interchangable.