Start here,
https://www.flickr.com/photos/advance-design_parts_co/sets/72157632210242370/ , then the tie-rods, then the King pins. A worn king pin is not ideal, but you can get by for awhile if not to badly worn.
With the weight on the tires, have a helper move the steering wheel back and forth while you watch to see what moves and what doesn't.
Caster setting can cause a lot loose feel at higher speeds, if the front end doesn't lift up when turning lock to lock while setting still, it probably needs more caster. Does it have wedges between the front axle and springs with the thickest part to the rear? It should have some, maybe a 1/4" thick tapering down to a point.
Joe
