Norton Transform fails on Wheatstone Bridge...help!

I have been trying to find the norton equivalent of a wheatstone bridge with the "bridge" resistor as a the load. The Bridge is unbalanced.

How do i find the current through the load when it is shorted to find the norton current?
It seems easy , but i havent found any ways of doing it.

I dont want to do a thevenin transform and then nortonize it.
I'm interested in knowing how to nortonize it from scratch.

Any help ?