For the W124 both the bearing and the rotor are larger than the sedans

I suspect, but can't say for certain that they are interchangeable over most years
Not clear if things 4matic or ASD would be unique.

Best to change out the entire assembly, getting the bearing placed correctly requires setting tools.

Rear bearing failure seems to be a random event. One failure does not imply the other side will fail anytime soon.

Only failure I've seen was on an 89 wagon with over 300k.

Jim

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14 E250 BlueTEC black. 45k miles
95 E320 Cabriolet Emerald green 66k miles
94 E320 Cabriolet Emerald green 152k miles
85 300TD 4 spd man, euro bumpers and lights, 15" Pentas dark blue 274k miles