I currently own a both a 2.5 T-maxx and a Lost LST, both nitro powered.
I am pretty sure a T-maxx transmission will blow to pieces stock, if you plan on using an engine more power than what comes with a stock T-maxx.
They can also blow to pieces if put under load such as cornering and braking.
I have never seen one in action or in person, but I bet a differential from one of these would hold up:
http://www2.towerhobbies.com/cgi-bin...I=LXGMP7**&P=0
Either that or you could spend some cash buying all metal parts for a T-maxx differential. The only things that are metal in a T-maxx differential are the gears and shaft, everything else is plastic and very prone to breaking. That setup might work, but it all depends on how much stress you put on it.
Look around I am sure you can find a differential much better than a T-maxx differential.
You might be able to find something on this site
http://www.harm-racing.de