Why shouldn't you use the differential...
 

...as a jacking point, if you want to raise the whole rear axle?

Anyone?

No reason, unless you are incapable of jacking it up without bending the cover. Don't do it if you have a tiny floor jack, because the car could easily start to sway side to side while jacking or if bumped, causing it to fall.

I wouldn't feel comfortable using this

http://www.sears.com/shc/s/p_10153_1...=30-47640260-2

but I would this

http://www.sears.com/shc/s/p_10153_1...9&blockType=G9

I have a craftsman aluminum racing jack and it's super stable due to the wide lifting area.

Thanks, I thought as much.

I do it all the time. Just don't damage the cover and use a proper floor jack as Moose said. I think Ford's reason for not jacking the car there is because someone might use a scissor jack, not smart.

You just opened a can of worms and people are going to crawl out of the woodwork to tell you why you shouldn't. I do it all the time. I put a phonebook between the jackpad and differential to keep from bending the cover.

You shouldn't do that. That is an improper use of a phone book.

When I had my tires put on a couple days ago, they lifted it via the differential.

If you do that, you'll void the warranty on the phone book.

It might weaken the seal and then you have the drip drip drip of 75W-140.
And you can't give the diff a shot to make it stop.

i've done it with no issues. As said, just use sense and reasonable caution and you'll be fine.