The only person I know that even advertised having some was Jack at Dead-Nuts-On. Think allot has to do with the liability concerns for vendors. Or just find your own and using new cups and bearing rebuild them yourself
Not sure of the question. Design is pretty standard though size and specifications vary with application
I was told by Jack at Dead Nuts On just yesterday "I stock new caps, bearing and seals that will fit directly on your original u-joints if you need them ($35.00 front & rear set)."
I was asking the same question as the OP ~ I have one original u-joint. For now I'm going to put new ones on, and keep an eye out for a 2nd original to restore as a set.
New ones at Napa are only ~$50 for the pair. They offer zerk-less "super heavy duty", and they offer some that have the zerk fitting in the end of the roller/bearing instead of sticking out of the center hub.
I have part numbers handy if you need them.