Drivetrain advice - Novak HV setup

I just recently put a HV novak set up in my emaxx.
I'm running 2 - 6 cell 7.2 v 3300 packs. Right away I hear something grinding when taking off and breaking, but I can tell if it's something in the tranny or just the diff's. My drive train is stock except for the CVD's. Those are all metal. I was just looking for some advice on what to replace first. The idler gears in the tranny, the gears in the diff, alum housings for the diffs???
Any info would be appreciated. Looking for the cheapest initial quick fix.

Thanks...