At last, after a long and hard search, I have finally found it.
What is it you ask?  Why its the Biggest the LARGEST Ranma fanfic ever.
Its size is 2,539KB and its called The Callers Plight a sequal to The Four
Birds of Fire
its located at the following website:
http://www.hcs.harvard.edu/~alhuang/ranma/fanfic/tcp.txt