Swapping In and Out Posts

I ordered a number of used kegs.

1 keg both had in posts and were 7/8.
1 key both had out posts and were 11/16.

Are posts interchangeable? Can you use an in for an out?

The thread size is different (at least on my kegs) between the in and out posts.

The size of the wrench doesn’t matter. The size of the threads do.

Here you go.

http://www.dresselbrew.com/Keg_Info.htm

The gas posts have score marks where you place the wrench. That’s the only way I know to tell them apart.