Hi loweman. Welcome to the forum. Is there a reason you think you caused this damage? If it just occurred on its own, suspect a worn universal joint between the upper and lower ball joint. There is at least one model of front axle that actually has enough room to remove and replace the joint without disassembling the entire hub and wheel bearing, but on most, you will have to remove the hub and bearing to pull the shaft out.
A really good / experienced mechanic can replace the joint in less than two hours. Typical cost of the part should be somewhere between $20.00 - 50.00.
June, 17, 2010 AT 7:58 PM
The reason I suspect damage is that I loaded the truck with firewood and drove uphill on grass until I reached pavement. At that point, I could not readily shift back to 2wd. I knew not to drive on dry pavement, so I attempted several times to roll in neutral to shift. The tires were scrubbing when I would put in drive to get enough momentum to roll in neutral. Because of the difficulty in shifting, I suspect I may have caused some damage. This is the only time I have had it in 4wd since there was snow on the ground.
June, 17, 2010 AT 9:21 PM
Oh. Scrubbing the tires in 4wd won't do any damage for short periods of time. It's prolonged driving on the highway the puts the driveline under constant stress. If doing what you did caused problems, every 4wd truck would be in the repair shop. It is much more likely the universal joint didn't want to be a universal joint any longer and was already thinking about failing. At some point, water gets into the cups and rust them and the needle bearings. The grinding action leads to one of the cups cracking apart. Due to its design, it can't actually fall apart, but it can cause lots of noise and a horrendous vibration. I suspect the little added stress of hauling wood was just what it needed to break. The problem would have occurred anyhow, just not at that moment.
A different problem these joints can cause is if one of the cups becomes tight from rusted or broken needle bearings, it will force a turned steering wheel back straight ahead every half tire revolution. That can be a weird sensation if you've never felt it before.