My concern is that should I drill & the tap doesn't hold at 12MM, where do I go next? At least if I do a 10MM and it goes wrong, I can go up to 12MM.

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David Hendy
'97 Renntech E60RS
'97 GMC 2500 Sub' Diesel
'95 E300D
'88 300TE
'88 250TD
'84 L/Rover 109