Jeff;

Extracting those bearing cups (especially the first time) can be tough...my only advice is to wet the joint with penetrating lube and keep applying removal torque with a vice grip...if this slips, try putting some emery cloth between jaws and cup (grit side toward cup) to help give VG a better purchase...remember cup and cross will be replaced by new U-Joint, so try to limit all damaging force to these components...they can be sacrificed...if necessary use a bf pipe wrench to extract cups...be patient...they must and WILL YIELD!

Notes on reassembly: Clean and deburr yokes in preparation for new cups and use a press or vice and cup sized 3/8 drive sockets to gently press them into place...add more quality grease into the cups before this operation, and a slight film of graphite grease in yokes will help them into place (and help extract them next time!). I also dislike the shock of hammer blows...it's a b**** when the shock of hammer blows dislodges some of the needle bearings...you know this because you cant fully seat the second cup...then you have to disassemble and start again (and with a U-Joint whose needles have taken a literal beating). Beware, if cross of replacement joint is the type with a grease fitting, cross only goes in with grease fitting pointing away from end yoke...ask me how I know...

Finally...inspect cross for "wear waves"...if you see 'um you have found the cause of noises.

Happy Wrenching!