Good Afternoon Mahfu,
You are correct! You will need the CF Battery Tray (766-126) and the Battery Tray Lock Assembly (200-420). Someone who has actually ordered the Battery Tray Lock Assembly will have to chime in and let us know if the Battery Tray Lock Handle (766-127) comes with the assembly (I'm guessing it does and has its own part number for those that loose the lock handle in flight). I am about to start the build myself and decided I will not be using more than two 12S packs as I can charge at the field in approx. 30 minutes or less. I am going to purchase another battery tray and lock handle just for the convenience alone. Expensive? Yes! But it is worth the convenience to me.
V/R,
Wayne Derrick