If you jack it up on the diff jsut be sure to get the jack on solid metal and not catch the edge of the cover anywhere. I've jacked all my Xs up for years like this and have never had a problem. Ford is just afraid someone will tear off their diff cover because they weren't paying attention and make Ford fix it.
Yes, however place the supports (jacks, jack stands, etc.) on the axle housings (tubes), not the differential housing. This can be done on both sides, but requires two support devices.
I'm glad to hear these replies. That's the way I've been jacking mine up, as well. It let's you throw a jack stand under each rear axle at the same time, plus there's hardly enough room to put the jack where Ford says to, and still squeeze a stand in there.
Why don't you jack up one side and put a jack stand under it? If you don't have them, they are real cheap at just about any place. Walmart, Target, auto supply places, etc. They come in handy for other projects too.....
