It sounds like axle is a torsion axle. You should jack up on the frame as close to axle as possible, NOT on the axle tube.
Because the frame is higher and as you raise it the swing arm will drop, it would be a good idea to have some extra blocking for setting the jack on so max lift is available. Short pieces of 2 X 6 work great.
"A wise man can change his mind. A fool never will."
"You only grow old when you run out of new things to do"
2018 Flagstaff Micro Lite 25BDS
2004 Nissan Titan