Looking on the 3racing site, they have M03M-01/LB as the part number for this part.
http://www.3racing.hk/products.php?products_key=2584
The rebuild kit they list as M03M-01RG.
http://www.3racing.hk/products.php?products_key=2584
I'll keep my fingers crossed that i don't need to start drilling the casings.
But looking at the casings i think your correct.
I don't see how the new diff is gonna fit without some modifications.
I've just measured my casings and drive shaft.
Unless they have made the external diameter of the drive shafts smaller i can't see how they are gonna fit without some modification.
The section that holds the drive pin looks to be very thick (4mm ish) so it is possible they could take some material from there.
But as the internal section is 6mm they'd have to make the external section 6.6mm to fit through the hole.
I can't see them holding up for very long at only 0.6mm thick.
So no doubt your correct i'll need to remove some material from the drive shaft hole
Cheers
Mark