Keg Posts

I just got some used corny's and one has 7/8 post( the 7/8 one has a 6sided nut on the out and a 12 sided on the in) and the other has 11/16 on both. They both say The Cornellius Co Super Champion on the side. I took the posts off and looked at the poppet's and both are Type B Cornelius style,

Soo the question is can i replace the 7/8 post with a 11/16 so i can have all one size ? How interchangeable are they ?

The 12 sided posts with the tri-square formation are for gas only. The internals are the same but they are machined slightly differently. They will work, but the black post wont fit properly, if you manage to force it on there it will be likely to get stuck.

What DAAB says applies if you are thinking of trying to swap a gas post for a liquid post, or vice versa.

If you mean you want to swap a pair (in and out) of 11/16" posts for a pair of 7/8" posts, you should be able to - I did this on a pair of my kegs, so all the kegs that I use regularly have the 11/16" posts and the one that I don't use much (due to damage) has the 7/8" posts.

Of course, this is only my experience based on my small set of kegs, I have no idea if the threads onto which the posts attach are all the same on every keg.