I am no Hulk and I don't try to be.
I have to loosen the gear casing until you ca see a gap between the two parts for the diff not to bind. In fact, upon the first build I was having problems with a layshaft spacer that caused the layshaft to bind... so I'm starting to think the gear casing is actually a little off. I wouldn't be too surprised about that, it came from the very first batch, and there were other parts with problem areas as well (wheels warped to a degree that they're not of much use for racing).
Could anyone measure their diff's width between the surfaces against which the bearings sit (without the bearings or shims), like this:
Ball Diff:
Gear Diff:
On my diffs it's clear to see the gear diff is wider. With shims on the ball diff and none on the gear diff there's still almost 0.4mm between the two. However, it could well be that the gear diff is just wider and my casing too tight, so I need to need to make sure.
I've also contacted Durango about this.