like i mentioned... the spring rate/manufactured shock may be different. as mileage is put on springs they will in way start to "sit" with time. one corner will not always sit the highest on vehicles. it will change from vehicle to vehicle put should all be withing a 1/8" to 1/4" of each other
__________________ - 2002 Z/28 M6 All Stock My Garage
"What your seeing in the photo's posted is more a result of the panhard bar style suspension which swings the rear end side to side as it compresses up and down. This can unload each spring and or both at the same time depending on the severity of the terrain and the way the car leans during a right or left turn. I've personally never seen an F-body that didn't have between 1/4 to 1/2" higher ride height on the drivers side rear. Also some times the springs can twist from their original orientation (lower pigtail facing forward) and cause an even more uneven ride height side to side."
the panhard bar may not be adjusted properly... it's always wise to get and adjustable one so you can take measurements and then center easier. all for corners should be within a 1/4" of each other once all said and done
__________________ - 2002 Z/28 M6 All Stock My Garage