IMO, using a floor jack, or anything for the rear axle to roll around is a big pain in the ***, because it has to come OFF that eventually. All I do is get the old rear axle completely disconnected first. Then I get each spring perch off the locating pins and get the axle just sitting on the springs in front of the pins. Next, I grab one side by the drum, lift it up and push the rear axle so the drum is now inside the leaf spring and set that end on the floor. Then do the other side and slide the old axle out of the way. Installation of the replacement axle is the exact reverse. To me, the floor jack just gets in the way.