ford-trucks.com is the Ford Truck enthusiast site. They have a good message board divided into the different years. Good people, lots of F100 knowledge Conor
What year F-100? FTE has some good people, but that site sucks. Nazi's run the joint and if you even suggest a part that does not advertise on their site they'll delete the thread and ban you if you do it again. Plus, waaay too many banner ads and junk.