I have in my notes from somewhere that the PSD reservoir filter is 964 355 183 00

-------
I have been searching the Porsche system for dealers with the PSD reservoir sitting in there stock rooms and buying them up. I have about five more either here or on there way. Because I paid extra postage to get them to me they are $45 each (plus shipping) if anyone wants one.
I have stripped down one of the reservoirs to get at the filter. Part number on the filter is definitely 964 355 183 00. This part does not exist in the Porsche system 8>(. It looks exactly like a small version of the smog pump filter with metal end caps. It has an O ring on the bottom and is held in place by a clip washer that can be removed using long nosed pliers. The filter is located in position prior to assembly of the reservoir as it will not come out of the neck. There is a small lip inside the neck which could be removed with a dremel (need to flush the reservoir after this action) to allow the filter to be removed and installed without any detrimental effect on the reservoir.
Now if we can only find the filter.
Roger Tyson

Here are some dimensions of the filter:
Height = 33mm
Diameter = 33mm
Hole Top and Bottom = 14mm
1 hole with embedded rubber flap (Checkvalve)
Pressed part number: 964.355.183.00
regards
Gordon

=========
We don't show the filter, but the reservoir shows up as P/N 928.315.013.01, at about $35.
Wally

====

Since the reservoir with filter is no longer available it makes sense to remove the internal filter and add an external like here: