On another note, the gears I used were the 3.9 gears from the old corona diff. They were in good condition and I prefer the ratio with the torquey motor, at least on paper.
People told me that I would need a crown wheel spacer up to 3mm, but you can adjust the pinion displacement out by just using a slightly slimmer bearing on one side of the carrier and winding it over on the threads. There is plenty of adjustment. Perhaps with a different ratio, the pinion is slimmer and you may need to use a spacer, but they informed me that was not required.
The bearings from the old diff were remarkable, just dead smooth races, but the cylinders themselves were showing some signs of wear, one even had pitting in the middle of it, I don't know from what, perhaps lubrication issues as they aged. There's nothing like the old Japanese stuff when it comes to bearings I think,