I've searched and found out how the auto hubs work and how to troubleshoot for a Vaccum leak. With hubs in auto, transfer case locks in but not hubs. I can manually lock hubs and they engage, but not on auto. I have done the vent/defrost test, passed. Checked my Vaccum lines at the hubs, passed. I guess my question is, can I leave it like this, every Ford 4wd I have ever had you had to manually lock hubs if you thought or knew you were going to need 4wd, then unlock when the potential was over with. I read the diesels needed to be fixed, mine is gas.

 

It sounds like to me that the hubs need to be serviced, ie greased. I have taken mine apart a couple of times and applied some quality grease to the inner working parts. It is relatively easy to do, but you just have to put them back together in the correct order.

2004 F250 ESOF Hub Service

Check out the above link on their service.

The only other part that I have replaced was the 4x4 Diff Switch (Ford 7C3Z9H465A, Dorman 600-402). It is located next to the vacuum pump. My problem was that when I activated the 4x4 the a/c would only blow onto the windshield. I got the part from eBay and it was very easy to install. It fixed the problem right away.

 

Mine too, $38 at RockAuto.com and two minutes to replace.