driving em out is better than pressing em out. Clips out, drive 1 side out aways so you can get at the cap & remove it then drive it the other way till you can get at the opposite cap. with the new ujoints installed they MUST be free in both planes (front yoke) and 1 plane on the rear ujoint. If not support the shaft horizontle just off the ground (so the ujoint/yoke is unsupported) then whack each ear (2) (connector piece between cap & shaft itself) with a BFH as needed till everyting moves smoothly. Hit one ear several times then turn the shaft 180 & hit the other ear. Setting the shaft on a bench supported along its length with the end you are whacking hanging free just over the edge works. Free in both planes means you move the yoke back & forth thru it's travel both ways (up & down & sideways) & it must be smooth then grab the rear ujoint & move it back & forth thu it's travel in the 1 plane
