NOTE: Many people will use a floor jack under the differential to lift the entire back of the car up at once, even though the manuals expressly says NOT to do this. People of have done it this way for years with no ill effects. But here is the reason why they tell you not to.
The rear axle is not perfectly straight. To allow the rear end to track correctly, there is about a 1 degree negative camber built into the rear axle. Basically what that means is that instead of axle being parallel with the ground, the differential is a little lower than the center line and the the top of the wheels tilt slightly towards the vehicle.If you lift the vehicle from the differential, you are putting stress on both left and right axle housings where they meet the differential, at the same time. They were not designed to perform in this manner. Although you may not break anything, you do not want to stress this area or slightly tweak it and remove or reduce this 1 degree negative camber.
NOTE: If you use the wide flat area of the front of the Kframe as a jacking point, be careful. If the jacking plate of your jack is not flat then you run the risk of denting this area. Doubtful it will cause any complications, but you will hate your self for it later.
