Update for you:
Over the past 10 weeks I have had zero luck with RemainInc listed above. Just got off the phone with REI (above post) and they can pretty much do anything. They buy their parts in bulk based on sizing, not unit part numbers, thus you can't order kits from them. You ship in master/hydrovac/steering box/ etc and they will tear it down and use the old seals to match to new ones and then rebuild the unit for you.
I was told to simply box up the parts and include a paper with my number and the necessary info, ship it to them, and once received they will inspect, call, discuss with you and then rebuild the unit and return. Seems simple enough. They seemed fine with including double/triple of the parts used to rebuild in the return box to have on hand as spares so you can rebuild it yourself again in the coming years depending on how heavily used the truck will be.
Located in Chicago, address at the link in my prior post directly above. Hope it helps
