8 3/4 install?

There are a few ways to do it.

Roll rear under car, place on jackstands, install springs at front, then swing up to rear shackle, lower rear down on top of springs.

Put it all together and jack it up, attach front spring mounts to car and swing up.

I've done it myself using both methods.

If everything is out, I would not mount the springs and then try to get rear in if by yourself. It's easier to do it using an alternative method.

Pick your poison!