I am previous owner of a 2000 F 150 and 2003 F 150 FX4. I have question in regards to frame. I have also done a search with no luck. Is the FX4 a fully boxed frame?

What does Carbon Steel Frame mean as well.

Thanks!

 

someone will correct me if i'm wrong but all F150s have boxed frames. so yes, the fx4 does.

carbon steel is steel where the main component besides iron is carbon.
http://en.wikipedia.org/wiki/Carbon_steel

 

The fully boxed frame became available in 2004 and is still currently used today.

http://www.edmunds.com/ford/f150/history.html