[MBZ] Correct tools for 124 half shaft?

[Werner Fehlauer]

I'm trying to remove the 6 machine screws that hold the inner end of the 
half-shafts to the differential on my '90 124.  The screws are socket head, 
splines, and a Torx 50 seems to fit (almost).  It appears to me that the 
screws have a 12 pt? socket head, while the Torx bits are 6 pt.  The result 
is that the Torx just strips out the head!

So what is the correct tool to use?  Any special techniques??
Any suggestions are appreciated....

Werner