Today's after-work project was to take apart the swivel hubs and inspect the parts. They came apart with no trouble, and the revealed parts showed surprisingly little corrosion or damage. The swivel balls did have some fairly deep corrosion on the polished surface, but only around where the oil seals sit, and could probably be repaired at some point and kept as spares. The interiors had no corrosion at all. The swivel bearings and pins are in good shape, in spite of not having bathed in oil in quite a while, but do have enough small damage from corrosion (and perhaps impacts) that they warrant replacing. I'm glad I didn't try to fill the hubs and swivel assemblies with oil, as it would just have leaked out quite rapidly: the swivel ball oil seals were all substantially damaged or worn.
This view shows one of the swivel assemblies, with bolts and sub-assembly parts bagged. That's the old swivel ball at the top; plus the old oil seal at bottom right, dented and perforated.
A view of the axle casing end, with the oil seal still in place, and needing the old gasket scraped off. Still a little oil in there! I'll have to order new oil seals.
