Re: front U-joint
If you need to replace the u-joint on one of the front axles, you need to pull the entire wheel assembly and spindle so you can remove the axle shaft from the front differential. It's a few hours work to do it properly.
For the left side, you'll have to remove the brake caliper, pads, hub, wheel bearings and rotor, and the upper and lower ball joints to remove the spindle. Once all that is out of the way, you can go ahead and slide the axle shaft out of the front differential. If it's the right side you may have to remove the stub axle depending on which u-joint is blown. To do that, you have to actually remove the entire front carrier from the I-beam. Not much fun!
While you have it apart, it would be a good time to just go ahead and replace the upper and lower ball joints as well as the seals.
1992 Ford Bronco
E4OD- B&M Stage 2 shift kit
Full 3" stainless Bassani Exhaust
32" BFG's/stock suspension
"No replacement for displacement."
"Our lugnuts require more torque than most Honda's produce!"