I'm coming from E34 and not as well-versed in later models. Researching diff gearset compatibility and understand there was a break between earlier 188mm and 210mm gearsets, and the newer "Kompakt" diffs as used in non-M E46 and E39 (M3 and M5 used the older 210mm gears, my homework shows). Are all K diffs the same for gear fitment purposes? If there were different sizes or other fitment categories, does anyone know about the 330d specifically?

End goal: to have a top gear ratio somewhere around 2.0:1, for use with a diesel swap. One option is an expensive and apparently fragile GS6-45DZ double-overdrive transmission. Another approach would be to fit diesel K gears into an older diff case. What I'm reading suggests that the opposite can be done.