This is probably not it, but on the W124, you can have different spring pads to adjust the height of the rear suspension. But by the sounds of it, it is most likely not this. This is quite strange since you didnt replace the springs. I would point to the shocks BUT I HIGHLY doubt they have enough pressure to jack the rear end up like that. hmmmm.....

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93 300D 2.5 Turbo, Black/Palomino 273K
09 E350 Black/Black 41K