I've noticed these are absent on my prairie. Does it say in the service manual that the rubber grease holding boots (for lack of a better word) are maintenance free? How would one grease these?

 

The simple answer to your question is : your not supposed to service them.

 

I once got a basketball air needle, and connected that up to my grease gun, and poked that needle into a non greaseable tie rod on a car that was getting stiff, but was not worn out.

I would probably replace any faulty joint on the quad before I did that.

 

There is an adapter at the auto parts stores for your grease gun. It looks like a huge syringe. You can get grease inside a rubber boot with it, but you really can't properly grease the ball-socket type joints.