I retained the stock ARAC4059 but there is a small tab on the inside close to the pinion and needed to remove it as it interfered with the metal pinion maybe it is a tad larger OD I didn't check the measurementsAwesome color choice. Choice upgrades too.
What yoke did you use for the new diff?
You shouldn't have to modify the yoke at all. I was gonna suggest using the Hot Racing yoke at the rear. I at through a set of gears using the composite version on my 4s Kraton.