my buddy has a 89 f150 4x4 with the x suspension in the front and he hates it. he wants to know if it is at all possible to to swap it out for a solid front axle.

 

Solid axle swaps are pretty easy, if you are a good fabricator. Usually best if you can grab a donor truck - gearing needs to be the same at both ends and whole axles is quick and painless. You also have steering components to deal with etc. Lots of good articles on the web - just be sure to bring fabrication skills.