I've put a 5mm x 30mm tape in the same direction as the bevel axis, so longitudinally over the seatings of the bearings, both in upper and lower half.
Way easier than taping bearing per bearing, and the tape doesn't move because it makes some 90 degree turns once everything assembled.
If the slop would be sideways, different story...
Again, still testing this...
And what type of gear-grease would be best to use on the diff ring? A sort of type instead of a brand would be nice, so I could buy some non-RC quantities of it
