Well I removed the u-joint and cleaned up the inside of the yoke and found the broken-off remnants of where there was a swaged collar to hold a plug as described above. I ground down the remnants to a flat surface and made a brass disk with a bleed hole, trimmed it to fit the remaining ID of the swaged area and then soft-soldered the disk in place. I installed the drive shaft, greased up the slip joint and when it got its belly full, it squirted grease out the bleed hole and all over everything else, just like any other normal grease-related operation. Must be fixed!
