At 141K miles the rear Springs shouldn`t too worn and saggy, but ya never know, and then you could have corrosion that can weaken them I guess.
I looked up the part numbers as I need to do this refresh project also.
123-350-01-75, $68.15 Meyle Sub Frame Bushing kit
126-352-01-65, $7.64 Meyle, trailing Arm Bushing (4 ea)
123-324-06-04, $55.88 Lesjofors Rear Springs
115-325-24-44, $13.92 Rear Spring Shim Genuine MB
xxxxxxxxxxxxx, $7.54 Meyle
123-351-14-42, $47.20 Meyle Differential Mount
I got these off another site. Then punched in the Part #`s with
www.benzpartswholesale.com our local Dealer.
http://www.partswebsite.com/benzpartswholesale/oemparts/mercedes-benz-137/1233240604-1153252444-1233511142-1233500175-1263520165.html
RUBBER BEARING 
Make: Mercedes Benz | Part#: 1153252444List Price: $14.50
Your Price: $11.60
Core Price: $0.00
REAR SPRING 
Make: Mercedes Benz | Part#: 1233240604List Price: $66.00
Your Price: $52.80
Core Price: $0.00
ENGINE MOUNTING KIT 
Make: Mercedes Benz | Part#: 1233500175List Price: $230.00
Your Price: $184.00
Core Price: $0.00
SUPPORTREAR SUBFRMEMETL 
Make: Mercedes Benz | Part#: 1233511142List Price: $162.00
Your Price: $129.60
Core Price: $0.00
MOUNTCONTROL ARMVLRUB 
Make: Mercedes Benz | Part#: 1263520165List Price: $17.50
Your Price: $14.00
Core Price: $0.00
The sale of a remanufactured part involves a core charge, this is a form of deposit until returning your old part. As long as core is not damaged, this charge is refunded when you return the core.
Hope this helps to compare MB priced to after market.
Charlie