Jeff ebay and craigslist are really good places to list. As for sites for info, depends what make and model you need info for. I for one use Fordtruckenthusiast.com for info related to my specific project, but find when it comes to customizing the guys(and gals Barb) here are the most helpful.
Also the wealth of experience here is tremendous as mentioned above. A lot of these guys have pretty remarkable bios and life long experience and skills.What can I say it's why I'm here for help on my truck!