1) Remove the axle shaft per Stu's instructions at D-30 Axle Shaft Removal - 1
2) Replace the u-joints per U-Joint Replacement - 1
. I strongly recommend the Spicer 5-760x u-joint. It is a direct replacment that is stronger & more durable than the OE Spicer 5-297x.
3) Do not flush the grease out with fresh grease per Stu's instructions if you go with the recommended 5-760x u-joints. In fact, don't even mix the caps up when you pull them, put the cap back on at the same location it came off of. That insures each bearing cap has the correct amount of grease in it.
4) Listen no more to that yahoo at work who said you'll need to heat the u-joints with a torch. Heat is not needed and the use of heat would likely just likely ruin the heat treatment of the axle shaft ears which are what hold the u-joints.