Automotive Forums

I own a Volkswagen and have the "Bentley" service manual. It is obvious that this manual is cut down derived from some far more detailed and comprehensive work. I have heard rumors that there are things called "Factory" service manuals which are the "real" manuals and are much more detailed and complete than the junk Chilton/Bentley pop manuals. However, when I try to find these service manuals I can't. How can I get them?

Also, along the same lines how can I find out what parts are compatible with what. For example, lets say I need to replace the coil. Can I take the coil out of a 97 passat and put it in my 92 passat? Can I take the coil out of a 90 passat and put it in a 92 passat? I need some kind of database or CD-ROM that tells me part numbers and compatibility for the parts in my car. I know the dealer has access to such a database. How can I get access?