I thought everyone must know about this site when I stumble onto it last week, but I guess not so here is the deal:

RockAuto.com

They have the best most comprehensive online part database I have ever seen. It cross references every possible replacement part and also shows what other cars also share this part by simply clicking on the part number, also if you click on the picture of the part it will give you a larger photo of each part. It tells you if a part was OEM or not and gives you the level of quality (heavy duty, etc). I was impressed that they showed 3 different options from 3 different companies on our front steering center link and a huge saving in price over our $200 OEM one at $120. I found it while trying to find the most options and best price for our PVC valves, lol. Everyone should check it out:

http://www.rockauto.com/catalog/raframecatalog.php