I'm in the process of swapping out the pump and motor on a D-200 for known good ones.   Removed the old motor today to discover that only the end flange of the strainer that sits in the transmission was actually there!     There's never been any signs of shredded screen when I've changed the oil, no fragments came out of the tranny with the last half liter or so of oil that came out when the motor was removed, and nothing I can see or feel in the casing. My guess then is that a PO has been here before me, found the screen came away from the end flange and discarded it.    I have another strainer that I can use but it's a different pattern.     The strainer came from a C-121 transmission though may not have been original to that - I can't say. I did discover that there are two different part numbers for these that have been used on the Sundstrands though the parts diagrams don't show enough detail to distinguish between them.   There was no evidence of a rubber sealing ring with this one when I removed it but it makes me wonder if the recess machined into the tranny case was the same depth when this type was used.     Can anyone with knowledge and experience help out here? I'm wondering if I should add a suitable O ring to make a good seal when using this one.   Andy