Joe,
Early on with our '04 Monterey I had trouble finding the hydraulic filter with the book part number or the number painted on the original. Turned out that the filter is so common on hydraulic machinery that there are a lot of sources. It shows up on everthing from log splitters to backhoes.
Among the easiest to find was the NAPA 1551. I never did find the OEM version. Beaver may have bought a big supply from an industrial source.
To change it, I put a pan under the filter to catch spillage. There was some, but not very much. Just be ready to screw on the new one as soon as you get the old one off.
Bill