dirt addict

1997 f150 4.6l , 5 spd manual trans.
I've searched and watched videos on how to, but I can't figure out if I need to lift the truck off the rear wheels, or can I use my ramps to raise the back end? Does the weight of the truck on the rear end effect anything in there?
Also do I need to use synthetic gear oil in the diff? 75w - 140....

Roger40

Is there away to the correct setting on pinion the threads and in. Pounds were taken