I see the recommendation is to use the rear diff for lifting up the rear using a floor jack. My question is which part is ok on the rear diff to use? In the pic below, 1, 2 or 3? Or any of the above?

Just making sure I use to the right part so I'm #$@#$@# up my diff.

 

Do not jack on the seam of the differential cover (right arrow in your picture). I always used the flat spot on the heart of the differential housing. I believe that is the center arrow in your picture.

 

Why not use the jackpoints at the side, where the factory jack fits?

 

That's where I put the jack stands.