if you have leveling blocks drive up on them to give you room to get the jack under the differential
I was just under my van ( Chev)
jacked up differential in stages ( front wheels blocked, in Park and e brake on
As I took it up I added leveling blocks to 7"- with wheels slightly higher
I have 2 sets of jacks stands- 4 ton ratcheting type ( careful with these), and 3 ton pin type
I can get the jack stands in place from the sides of the vehicle, 2 on each side.
the pin type set to height, I lower the van onto them
and raise the ratchet type up to frame as secondary support.
the wheels were lowered to the 7" blocks
and was then under the van replacing the genny fuel line and petcock.
and a general examination, admiring of the Pleasure Way work under the van
after that, I raised the diff slightly to remove the 3 blocks each side and lowered the wheels to them- I had some suspension work to do ( supersprings sumo)
removing was lift by diff, remove jackstands, lower van slowly
you may lower onto leveling blocks so you can drive off them once jack is removed