Silly me

IIRC when I looked at this problem, the most appropriate M12 fittings were for 1/4" pipe, not 3/16".

What I didn't do was look at Ford supplies.

They list male nuts for 4.75mm (3/16") pipe in 'standard' M10 and M12.

M10 - 6758611

M12 - 6758609

Sorry, my hacked Microcat doesn't give prices, but even Fraud couldn't charge more than a fiver each...

Martin

PS. Just been picking up parts for the w/e. Quoted for 6758609 - £2.15 +vat each.