Hey all.
I have a 99 f250 v10 4x4 and I'm having an issue with the lockout hubs. The truck came standard years ago with manual lockouts that have sense been replaced with mile marker lockouts. Problem is I can unlock one and not the other. I have taken the hub completely out and it turns fine but when I put it back on the axle I cannot unlock it. What could this be? Also probably related when I drive it with it locked in and the other locked out and the transfer case in 2wd I get a knocking sound coming from the side with the locked in hub.

 

Pull both hubs and check for possible missing parts on the hubs and the axles.

 

If it rattling when in 2wd and not in 4wd, it could be your stub hub shaft bearing.
These need to be lubricated regularly and when not, they will start to chatter and make it difficult to operate the manual tabs.

 

I think you're on the right track because I've never lubed anything down on that side. Is that the shaft right behind the hub?

 

Yes, the bearing is behind that assembly.