Sorry for late reply
we do regularly see problems with removing the front diff drain plugs.
Either they have been over tightened, and/or been previously butchered.
You see sometimes they can't put the tool in all the way, no good.
Usually i use a good 10mm hex head socket, add a chisel if needed.
Today I thought I would try Roos nuts, it's a special tool from http://www.tnnengineering.com/
It worked really well.
It basically converts a10mm hex to a 24mm socket.
Because of the flat surface it helps keep the tool square.
FRONT DIFF DRAIN PLUG
So I put a new plug, I prefer to start fresh as I'm looking after this vehicle now.
The tool was nice n tight, just the way you like it.
I'd say a good investment for d.i.y & technicians alike.