Sometimes, an ordinary differential just isn't as tough as you need it to be. There are several large, heavy duty differentials on the internet, like this one at Technicbricks
Unfortunatly it uses some uncommon parts.
Thats why I designed a heavy duty differential with more common parts .
You can download the LDD here:
Note: the green parts in LDD are optional, they make the diff a bit more sturdy, but less compact. Use them only if you got room to spare. Also, don't forget to remove the other half of your turntable, I couldn't do this in LDD.