2000 A6 2.7T driveshaft removal

[Dave Fain]

My A6 has the dreaded center support wobble.  I have removed the exhaust
and all the heat shields.  The Allen head bolts on either end of the
driveshaft refuse to budge.  Before I get a bigger wrench and strip out the
heads, are they installed with Loctite or something that would require
heating?  I was expecting to see Torx fasteners but they are regular Allen
head bolts.
thanks,
Dave