One more thing
Your car probably does not have it or else you would have mentioned it, but some W124 sedans and all W124 wagons got the hydraulic self levelling rear suspension. A common failure with this system is the accumulators (air cells or nitrogen cells). The symtoms are initially an underdamped, bouncy ride which deteriorates into a hard, bouncy ride. Having recently replaced ours, I can assure you the difference is dramatic. The ride and damping is now superb. It is amazing when you observe how many W116, W126, W123 wagons and W124 wagons are driving around with bad accumulators. When you follow them on a freeway you can actually see the rear bouncing on the slightest imperfection in the road.
107.023: 350SLC, 3-speed auto, icon gold, parchment MBtex (sold 2012 after 29 years ownership).
107.026: 500SLC, 4-speed auto, thistle green, green velour.
124.090: 300TE, 4-speed auto, arctic white, cream-beige MBtex.
201.028: 190E 2.3 Sportline, 5-speed manual, arctic white, blue leather.
201.028: 190E 2.3, 4-speed auto, blue-black, grey MBtex.
201.034: 190E 2.3-16, 5-speed manual, blue-black, black leather.