Rear suspension/Ride height

Was jacking my 71 by the pumpkin to get some underside cleaning done. As I was jacking noticed that the rear axle seemed to be hanging lower on the right side. As I let it down noticed that the right side settled flush into the jack stand while the left side settled with about 1/3 inch clearance on the other jack stand. Measuring further confirmed what my eyes and then the jack stands were already telling me which is the right side hangs further away from the body than the left side.

I'm guessing that:

1) the arcs on the rear springs are different (shouldn't be because they're new), 2) some of the attaching components for the springs are not adjusted properly or 3) There's an issue with the body.

Are there any other possibilities that would cause this? What should I be checking?

Was the car on a level surface and the front at a uniform height? Because the front is heavier if it isn't level it can cause this kind of issue in the rear.

I would make sure the spring centering bolts are in the holes in the spring mounts. With the jack stands in place I would loosen the spring u-bolts a turn or two and then re-torque, just in case there's a binding issue. If you have pressurized shocks I would make sure they are both still holding pressure, also make sure the shocks move freely and aren't binding.

If you are seeing different gaps in the rear fenderwells with the car on a jack under the center of the rear axle and assuming the front of the car is level, then there is something funny going on.

As Don suggested, since the springs and their attachments are what control ride height, there must be a problem there.

Make sure that the front is level or on the tires, and then look at the wheel arch gaps. If you do have gas-charged shocks, they'll contribute to ride height, as well as the spring mounting bushings to a small degree (if OEM style rubber, those should be tightened with the car on its tires, not unloaded).

Worst case is a body issue with one side having a shorter distance from mount to mount, this side would have a higher ride height...

I often see this on my car, I put it down to fact that the axle is heavier one side than the other (because the ring gear is on one side of the pinion) or maybe the staggered shocks?

You have to hold your mouth just so when you tighten everything up-that's your problem

Thanks for the info and suggestions. Going to do some adjusting this weekend if i have time.