Strange post on Ball Lock

Kegging
1

I picked up some ball lock kegs from a person who was getting out of the hobby, on one (or more) of the kegs, there is a strange sized post. The post is 5/16ths and the ridge where the balls drop into is a bit bigger. I pushed on the gas connector and it stuck like a fish hook. It took me 15 minutes to pry the connector off.

Of the three that I was working with, this is the only connector that I found to have this problem. All the other ones were the standard 7/8 hex and star type.

Anyone run into one of these dandies before?

2

What are the markings on the keg?

Have you tried swapping the post from keg to keg to see if the threads are the same?

3

The posts are interchangeable, its is very strange. The post seems to be a 3rd part post that is just a bit bigger. It can get really stuck and I think my dremel will be grinding them a bit.