Front Posi Axle. How to tell?

[JimmyFloyd]

Ok, so I had a guy come buy the center link on my suburban, and he looked at the axle, and said it looked like it had a Posi tag on it. I am interested to know if there is a tag that denotes it as a posi, or if there is another way to tell? If I have to open it up, will it look the same as a rear posi carrier? It's a D44 axle, appears stock, but I know the rear appeared to have a gear change.