Paul, it surprised me as well.
The springs are from FastLane, OEM MBZ matched to the car's VIN #. The ones I took out in comparison to the new ones were exact: Same height and same color codes painted on them.
The only other possible thing I could think of was that when the rear susp was disassembled that the bolts were not exactly re-located where they once were?
Any one have this experience?
BTW, I am very satisfied with the ride quality improvement. This was one of those "Hmm what do I need to do to fix this ....." and except for the small amount of reduction in the rear ride height, it is great!