Use a 12 point 13mm socket. Soak the seam where the bearing meets the knuckle real good with penetrating oil. I keep a few 'sacrificial' bolts to beat on, so as not to ruin the originals. Remove the original bolts, install the beaters, and tap them and the perimeter with a BFH, and it SHOULD come loose. When I reassemble mine, I put a dab of anti-seize on my finger, and massage it into the knuckle's mounting surface. Not enough to drip or ooze, but almost dry. While you're at it, think new unit bearing. Murphy's Law dictates that as soon as you're happy with the u-joints, the bearings will start laughing at you. Ask me how I know (more than twice!).......