I found exact replacement Shepard Power Steering unit rebuilt ready to go at Weller Equipment Tampa Fl.813-685-6100.
I believe they have other shops throughout the Country.
They are an excellent company and comes with a warranty. They also rebuild Allison Transmissions and many other parts.
I had great luck with them.
2000 U320.
Hope ot helps someone.
Josams Chassis works in Orlando did the removal and replace. They are a first class shop.
Weller Truck Parts