O/drive extension

["V.Hughes" <v.hughes@student.canberra.edu.au>]

I had to replace the rear extension on my overdrive (Series 3) because
some previous owner had apparently dropped it, bending the housing out
of shape where the tailshaft fits.  The new (pre-owned) housing is
identical EXCEPT there is a 3/8 inch threaded hole in the left (ie
passenger) side which is not in the original.  What is this hole for? I
intend to seal it (short bolt and sealant) - does anyone foresee any
problems?

Vic Hughes