You're in luck! I still had this on file:
click image to enlarge
The part you want is included with some other parts and can't be had individually.
These are from the LifeLike version, but should be the same for Walthers, however Walthers still may not have unpacked the parts, so they may or may not be available. Good Luck!
You might also try Precision Scale (Bowser) or Overland for brass parts. The oil cooler line isn't that difficult to bend with .015 or .019 wire using some eye bolts (Detail Associates) to mount it
Jay
C-415 Build: https://imageshack.com/a/tShC/1
Other builds: https://imageshack.com/my/albums
Can anyone tell me the part number for the cooling coil on the P2K SD9? I have contacted Walthers but could/would not help me without the part number. I have five RailPower Product shells without this detail I wish to add so I can continue on with my project. Any other sources know for this part would be helpful.