Clunk could be alot of things as said before plus loose fastener on the shock mounts, or loose fastener ANYWHERE in the steering... I would check the pitman arm nut first. The pitman arm is press fit to the sector shaft on the steering box by the pitman arm nut. After it has been removed and replaced, it may need to be re-torqued as it settles in. Have someone turn the wheel back and forth as you watch the front suspension and steering from below... if there is ANY free play in ANYTHING!!! your truck will wander/bump-steer. If the steering wheel turns, the pitman arms needs to turn at the same time or the steering box is shot(I replaced mine with a remanufactured from Advanced Auto and it is shot after 3k WITH the DSS!) Look at the tie-rod ends and drag links. I wouldn't worry too much about the alignment until you are SURE it isn't something that is loose or worn out... I haven't found a shop yet that can give me an accurate answer for steering problems with these trucks!! Keep looking around and asking questions here before you go broke with alignment shops! I also agree with the lower control arm bushings being shot but this could be difficult to see unless you put the truck on stands or a lift... Keep us posted.