Monkey Wrench Racing suggests the following parts for a 2003 3rd and 4th Gear Upgrade on an 1999 to 2002 C60 Gearbox.
 
3rd drive gear                       33034-20071
4th drive gear                       33035-12190
3rd gear synchronizer ring     33368-20090
4th gear synchronizer ring     33368-12210
No. 2 sleeve                         33364-12051
 
These parts would be for an American C60 box. Would you use these parts for the same upgrade on an Australian C60 box?