Jacking Points
I cut down a piece of hard wood so it will fit in between the threaded portions of the rear axle spring U-bolts. Then I use that as a spacer between the floor jack's lifting pad and the axle.
I use the same setup on the driver's side on the front axle. I put the block right up inboard of the axle tube U-joint yoke. On the passenger's side I use the bottom of the lower link-coil mount, with a thick piece of rubber acting as an anti-chafing pad between the jack and the mount.
I'm always a little leary of using the differential housings. Not knowing that much about their strength, I'm concerned about maybe permanently deflecting an axle tube 0. 010" or so.
On the rear axle, this shouldn't be a problem due to the minimal weight on the rear of the truck. On the front axle, we have 1,100# of engine and all of the other stuff to lift too. I'm not too keen about using the lower link-coil mount as a jacking point, but its better than that tube coupling area of the front axle disconnect.
I weighed my truck (empty) once with me in it and with a full tank of fuel. There was 4,750# on the front axle, which is rated for 4,850# (I wonder why the DC Bean Counters didn't try to save a few more pennies per unit and try to get a 4,800# front axle). There was 2,000# on the rear axle.