think the drive cups are a different depth from the gear diff to the ball diff, but I forget which way





I thought so too I've tried it both ways and then using the ball diff and well as the stock bevel set... I spent close to 4 hours trying to figure this out..
I tried the following combos..

Stock steering arms, Tamiya universals, metal bearings, stock and ball diffs
Stock steering arm, Tamiya universals , plastic bushings, stock and ball diffs
metal arms, Tamiya universals, both types of bearing, stock and ball diffs

I broke one of my stock dogbones.....