As I posted in your first thread....
Unless you plan on actually going all out and rebuilding the Thundermaul innards, then don't even think about using a Lipo on it. It'll just break, and fast.
It'll fit, but the Thundermaul is the most goddamn annoying AEG out there to put a battery into.
Why not just use your first thread to ask questions about the gun instead of making a bunch?