Complex Password Filter

I have been asked to modify the strong password dll (passfilt.dll) in our Windows 2000 forest. However, I have thus far been unable to locate passfilt.dll (this .dll is referenced in Q161990). We have not turned on the password complexity requirement as of yet due to the need to modify the filter. I have searched all of our domain controllers for this .dll file with no success. The knowledge base article provides instructions on how to modify the .dll in NT4, and that it was ported over to Windows 2000.

What am I missing here?