Thanks all for the information. I'll give the u joints another chance since it is something I can do. My truck is single drive shaft, from the end of the transmission to the differential. Used for work and never wild joy riding. Hopefully, the drive shaft is still ok. My guess why this u joint failed so early is that I didn't grease them. I did handle the bearings and the cups although I didn't wipe away the factory grease. There was grease in the channels (it was greaseable) but kind of light in the bearings. The vibration was fixed with the new joints at that time.

 

Grease fittings have disappeared everywhere because it was discovered back in the 70s that parts wear MORE due to contamination introduced during greasing, than they do from loss of grease. So a sealed part wears less & lasts longer than a greasable one. The problem is than no one cleans the Zerk after greasing, so the grease left on it collects grit. Then the next time it's greased, that gritty grease is the FIRST thing that gets pumped inside. Even if you wipe the Zerk before connecting the gun, the grease & grit around the check ball stay in the tiny groove, and get pumped in. So the best thing is to eliminate the grease fitting, and just keep the clean grease inside. If you really feel the need, you can disassemble the joint, add fresh grease to the caps, and reinstall it.

But it's not necessary, if you use quality sealed u-joints, and grease them during initial installation.

 

Car makers do not care about anyone's greasing habits, besides nobody ever had to tell me it is wise to wipe the grease or dirt off the fitting..Only a fool would go through the time to disassemble the joint , pack the joint with their dirty hands and reinstall that same old part. Grease fittings have been discontinued to save money and labor costs on the assembly line. Unless those joints were captured within the companion flange, the joints had to be greased by a lineman at the time of assembly. No matter what type of joint was used, very very few would fail within the warranty period. Same applies for the non greasable front end parts which very often wore out at low mileages. It's all about saving money when it comes to auto building.