clunking sounds while making turns can mean many things, none of them any good...
but if you could give us a bit more info? coasting into the turn, pedal to the floor into the turn, 2wd or 4wd? ex wife/ girlfriend tied to the front fender flopping around?
without more info on your driving habits, the truck itself, I would look at the obvious first:
make sure the wheels are on tight. could be a few loose lugnuts. simple and easy fix.
look at your shock absorbers and springs. you could have a broken shock mount.
look at the tie rod ends and ball joints. jack the truck up and put your hands on the wheel at the 3 and 9 o'clock position and try to wiggle the wheel. if it moves and you feel it, the tie rod is worn. Next do the same thing with hands at 12 and 6 o'clock position... if it moves and you can feel it, ball joints are worn.
And not for the ball joint/ tie rod check, even if the don't move that still doesn't mean that they are not worn out, but this will give you a bit of a clue.
Good luck, and let us know more of the particulars.
AJ