Well, I got my truck completely fixed, and it's damn smooth now. I got up to 90 mph on the highway right after I finished installing the new u-joints, and the driveline didn't vibrate one bit. I had to jam one of the u-joints into the yoke pretty hard in order to get the retaining clip to seat, and afterwards I could barely turn the joint with my hands, but it seems to work without any problems. And so far, not a drop of oil has leaked around the new oil seal.
That bolt from my car ended up being the one that connects the control arm to a bracket on the frame, so I'm damn lucky that I made it home without incident this morning. I guess it was actually better than it being from the tie-rod, 'cause I would definitely have wrecked if that were the case. None of the auto parts stores in town carry such specific items as that bolt, and even the mining equipment supply store couldn't find anything like it. When I go into work on Thursday, I'm going to stop by a junkyard and get one, plus a new rim if I can find one. The right-front rim on my car is bent pretty badly (the vibration from which probably caused that bolt to come loose), and a small part of the tire is worn down to the steel belt.