#10 That's interesting Geoff. My 2015 6 speed has 1 x M10 and 1 x 3/8" hex plug!
My BMW diff doesn't have a drain plug.
Three years makes all the difference between a 95% & 100% metric chassis ? Sorry Diff fill plug. (ammended)
My chassis was hardly metric, Geoff, I'm not sure that exists. *smile*.
It's hard to understand why they changed just one of the two plugs in the 6 speed too!
It certainly is metric - just a bit unsure if it's M18 and not M20.
Blatchat Google Search
Sierra final drives have all metric fastenters, CC merely machine off the re portion of the OE cover
I use this one, much much easier access with a ring spanner