Can you mig weld on a good sized nut. Say 3/4"
It will give you something to turn and the heat will loosen any debris on the GP.

The trouble with me drilling one is that aluminium is a lot softer than the steel.
Good luck

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85 Merc 300D - Unwinding 31 years of wear
86 VW TD
Mahindra Diesel
Iseki Diesel

In 2007 I didn't own a diesel.