If you are referring to the big "heim type" joints the RE's are unique.
They can be disassembled and rebuilt easily.
It helps to have their tools - 2 sizes.
Simply loosen the lock screw, unscrew the side cover. Inside is 2 nylon pieces and a ball with a bushing through it, if badly worn they are replaceable from RE, not expensive at all.
Lube them up good with a quality grease and reassemble.
There is a Zerk to shoot grease in, make sure the passage is clear - run a small drill bit down through the Zerk's hole to make sure the hole is open all the way to the ball so the grease can get all the way in.
Be sure to tighten the lock screw.
Properly greased and kept tight they should last a very long time.
I love them. About every 10,000 miles or when they get noisy they should be greased and tightened a little with the tool.
They did have a problem with the standard type bushings a couple of years ago, but that problem has been solved.
Caution - never use regular grease on rubber bushings - the hydrocarbons in the grease destroys the rubber. Always use a soap type or silicone lubricant on rubber.