Brushless Monster gt conversion help

Bought a mgt on ebay for 400 bucks setup very nice... Going to sell the .70 engine that came with it and some other stuff. Started working on it today took oout the tranny electonic box, servos and engine. Installed my quarter scale servo conversion mudguard and servo. Will Take progress pictures.
I am going to install a center diff. Have not decided which diff to install.
1. Has mike made the center slipper for the diffs yet? Having hard time getting a hold of him.
2. will a center diff alone be good enough or will the drivetran exlpode from from not having one?
3. 5s or 6s lipo? Not sure if 5s will be enough power.

http://cgi.ebay.com/ws/eBayISAPI.dll...m=330286046842
link to truck I bought