my dad has a 1990 f150 with 384,000 miles on it, it has the 5.0, everything(motor, trans, rear end) is original to the truck nothing has been rebuilt or replaced expect tune up parts and the normal crap that goes out it runs great but it has alot of play in the steering wheel what could be causing this??

 

Unlock the steering wheel, lift the hood, grab the intermediat steering shaft, rotate it back and forth and look for play in the upper and lower joints. Continue doing that and look to see if the pitman arm on the steering gear box moves with the steering shaft, this checks for play (wear) in the gearbox.
Get a helper to rock the steering wheel back and forth while you get under the front end and check for play in all the steering linkage joints.

 

I believe there is a Rag Joint, and a Slip Joint.