I have a 02 f150 w a 4.2l v6 2wd. I was wondering how hard and expensive it would be to convert it to 4x4.

 

It's not worth it, just get a 4wd

 

I second this, you would surpass or come pretty close to passing up the value of your truck by doing this

 

Everything I have read about the conversion has boiled down to it being really expensive compared to purchasing a 4X4- with the exception of one thing;

If you are purchasing a vehicle and are planning on replacing more or less all of the stock components like axles, drivelines, transfer case, blah blah blah, with aftermarket stuff, it might possibly make more sense to just get whatever is available as the base (including a 2wd) and going from there.

But that is a fairly rare exception to the rule "just get a 4wd" and is really predicated on the assumption that you would have the money and/or need to do all of that work in the first place.