If you are using the inner tube to replace the rubber boot, get the largest
size inner tube you can get for a bicycle.  A "standard" mountain-bike inner
tube is a little bit small, and will wear out quicker.  Road bikes are right
out.

Cut about a 6" section of the tube, and slide all of it down over the cup
part.  Put a bunch of grease in the cup.  Insert the ball part and slide the
inner tube up over it.  Use the zip-ties, or wrap with wire, at top and bottom.
If you look at the cup part, you will notice a groove around it that the
original boot sits in.  That's a great place for the zip-tie to go.  You're done.

Bill Marshall
85 GL Tiico "Pandora's Box"
Aurora, IL