A little progress on the power steering pump and reservoir. It was just happenstance that in my searching, I found the pump and reservoir combination I wanted on the Autozone site. It appeared it was something that could not be ordered, reason unknown, but at least it showed that it had existed. I checked with the local store and in fact it cannot be ordered under the part number that comes up when the Riviera S/C is entered. The one thing it did give me is the "Endurance" moniker, apparently the Autozone house brand. A Google search on that comes up with BBB Industries, much like Cardone apparently. In any case, I called BBB Industries and got their tech line. A nice guy named James, who apparently had been around the block more than once, understood exactly what the problem was without a lot of explanation. He stated the reason for so much of the confusion comes from one company being bought by another then another and along the way each one consolidates and streamlines their offerings. While this is going on, part numbers get lost and big mistakes spread throughout the parts industry. That gets baked into the systems and inexperienced parts people only are presented with items that appear as correct for the vehicle used as the search criteria.
He stated they do lots of things for many outlets, and gave me several part numbers, one was for Autozone, and when they entered the number, sure as can be, the correct item appeared. Now this is a pump and reservoir assembly and I opted not to pursue the tank alone after speaking with the rebuilder person. The new one will be here tomorrow. He did mention he saw a tank only available from Cardone but it was $70 which he stated was outrageous, since the assembly with pump is +$12. The topping on the cake is, when this part is entered under the Riviera S/C search, a big red flag comes up that says it is not compatible. For the very small number that may be interested these are the part numbers:
Autozone: 6358
NAPA: 38-1340
Delco: 36P1528
As you can probably tell from the above, these are all the same part. All show as available.