You answered your own question. The W140 is bigger (heavy duty). I'm not sure about the bolt pattern, but I think the front pinhole is bigger in diameter on the 140. Do yourself a favor and buy the correct one, they are cheap. BTW, if it's not broken you can regrease without removing panel by using lithium spray with a small nozzle tube. The trick is to get the door as closed as possible while spraying grease.

Vin