My '81 leans to the passenger side. I have a new Rubicon Express 4.5" system. After swapping the rear springs (side to side), the lean is the same - confirming it's not suspension related. I DO NOT want to lower the driver side to match. That would make the Jeep look like it's squatting - if it were assup, I'd be okay with that. But, it sits dead-level on the driver side now... and sags in the rear on the passenger side. Lowering the good side is not an option.
I talked to a very reputable spring shop (makes/repairs/installs springs for trucks, etc.). After asking a lot of questions, e.g. "Have you swapped springs, is there an invisible fat man in the backseat... " He had two suggestions:
1. Remove and re-arch - increase the arch - in the right rear spring. Essentially, add some more lift to that spring and level it up.
2. Add a leaf to the pack for the same result as above.
I asked the guys who work on my CJ (they primarily build/restore Land Cruisers) about having different spring rates in the rear. They said it would not be unique - some trucks come from the factory with different spring rates to accomodate offset loads, e.g. fuel tanks, etc. They agreed it would or could present issues on the front, but really doubted I'd ever notice it in the rear - even under hard acceleration or braking.
I'm on the fence which do to do - add the leaf (which will lift by the amount of added arch, but lower by thickness of leaf) or let them re-arch a new R.E. spring. Not the end of the world if I don't like the result - and have to buy a single spring from R.E.
The only thing I'm sure of is it HAS to be fixed. It really sucks to have all this time/money in the Jeep and consistently get comments like "Man, that's a sweet Jeep... why does it lean to the right?"