[Jimmy58]

I have used a Hammer in the past, but it is a real bear with the nylon locks gm uses now. I assume that the joints havn't been changed before? If not you will have to use a torch and heat the ears where the bearing cup goes into the ear till the nylon starts to ooze out. Make sure to heat evenly all the way around and then using a big drift and a big hammer punch out the brng cap and procede to the other side. Make sure to mark the shafts so they will be reassembled in the same orentation as they are now.
Using a press is easier but not everyone has access to one. You can buy u-joint presses that works like the ball joint presses on e-bay for not much money and they work quite well.
When it is time to reassemble the shaft I would use a press and not pound them together as the potential of ruining the bearing is very high. make sure all the c-clips are well seated and grease the fitting after you are done. This is a good time to change the rear seal in the tranny/transfer while the shaft is out..
good luck
Nick