84 First 42 Rudder Shaft

Nov 25, 2011
17
Beneteau First 42 0 In Transit
My 1984 First 42 (built in France) has a 4" did sold rudder stock.
I want to drop the rudder in next haul out.
The top end of the stock has a tapped hole for an eyebolt (to use
when lowering the rudder).
Can anyone identify the size and type of thread tapped into the top
end of the rudder stock ? This is a female thread, assumed to be
metric. A 16 mm thread is too loose and 18 mm won't fit ?
please reply, safeships2@yahoo.com