You may have to get a low profile jack, or you can try either over inflating the tires to gain some ground clearance or placing some two by tens on the floor and drive on top of them (that will gain you an 1 1/2" of height.
If the pinion angle is bad and you are getting an
oil leak, then my guess would be that the U joints are starting to fail and that is causing excessive movement in the yoke which then is disturbing the seal on the output shaft.