Thanks everyone for all the help. I drained the reservoir (most of it onto the floor... cause I'm lame..), managed to get the filter
out to take down to the truck parts place to get another one. FYI it is a Napa Gold #1487 or a Donaldson #P550487. Of course the bolt was buggered up and the rubber washer that holds down the cover was toast so after chasing down replacements and machining washers etc.-- I got-er done! Like most Bus projects they start to behave once you take it apart, put it back together and know how it works!!
I knew when Art said it 'd take me an hour I should be prepared for 2+ and a little bus chaos...haha
Anyway, the next challenge is the AD-2 Air Dryer that needs some sort of love since it discharges violently every minute or so. Problem here is it's buried and the pre-project is uncovering it....ahh the bus life!!
All worth it if we can use it this holiday weekend.
Thanks again for the help.