I think these links to an Electronic Parts Catalog, will be useful to people who want to look up information whilst doing work on their cars.
They are nice exploded drawings. Not sure the Prices are up to date however.
Mercedes Benz EPC Type R170 170 Information Everything Benz
Mercedes Benz EPC Type R171 171 Information Everything Benz
(REGRET NO INFO ON R172)
OPEN LINK Above.
Then Choose your sub-model
Click on Left Hand Side Column) - Picture of item & Price
Click on item in Main Column - Major Assembly Group (NOTE Use ALT LINKS tto avoid Russian text)
Another link that may be useful to you.
Here they say you can search more than 1,000,000 hand picked Mercedes-Benz pages filtered from Google -
For those that use it if Firefox Browser causes problems USE INTERNET EXPLORER for this.
EverythingBenz - Mercedes-Benz Forum and Web Search Using Google