Was doing the baseline on a 96 cruiser the other night and wanted to force out the old grease... Worked well on the spiders and the front slip joint. Was working as usual on the rear slip joint, then.... POW! .... Grease pours out into the middle of the u-joint. Blew the seal- first time that's happened. Pretty sure that there was some very bad crud in there that prevented the old grease from continuing to come out through the slip joint. Probably still not a bad idea when I want to get water out on a truck I own and know, but I'm gonna alter my baselining procedure for sure.
Now what, indeed...
I had the half dollar-sized steel blank seal blow out on the F driveshaft on my 60 a couple decades back. I had it welded back on at a drive shaft service shop. They also serviced the u-joints and re-balanced the shaft at the same time.