With Savages it's not just the diffs, but the low quality of the entire drivetrain.  The cups, the bones, etc..  I've given up on Savages, because I don't want to replace all the cups every 2-3 gallons.  The diff issues, as mentioned, also have to do with driving.  Don't land at WOT from jumps,etc..

This is from three gallons(I think.., mighta' been five, but still, unacceptable..) with mere Axial 28's..: