Before I would give up on the ESOF hubs I would do the maintenance as referenced by Sddesigns in post #13. I had a bad hub experience last week in the snow with my X. My ESOF would not stay engaged in 4wd. The hubs were stuck in auto and I could not manually lock them in. I finally got some liquid wrench(or WD40) and a pipe wrench and sprayed thoroughly in the cracks of the hub and ever so slowly worked the hub until it started to move. Then I locked the hubs in. I do like the ESOF hubs better than the old auto hubs because you can manually lock them in. I have not had good luck with Fords Auto hubs. They do not seem to work for me when I need them. My 96 Ford F250 Autohubs would stick and not engage in below freezing weather sometimes, causing alot of aggrivation. I ended up having them replaced under warranty, I wanted them to replace them with manual hubs but they had to replace them with stock autohubs. Next chance I get I am going to take my X to my local mechanic and have them lubricate the ESOF hubs so I can turn them with my hands. Sometimes it helps to read the manual and understand what you have to do to engage them. I realized that you should not shift on the fly in below freezing weather but rather stop put it in neutral then turn the switch, similar to turning from 4H to 4L. Sometimes it takes a few seconds for the vacuum to "lock" the hubs in.