When I got my replacement springs they were marked left and right. If you looked at the spring pack closely you could see that they were arched a little differently.

The rear springs on mine are still the originals and the front bolts on those springs will not come off with out the use of the Blue wrench (cutting torch).  I noticed after I put my SPOA on it that it did not sit level in the rear.  When I added the springs in the rear I added the extra small leaf on the passenger side to level it.  

Brent