Upper Transom Rudder Fitting Question

I have been sailing a Scot for the past couple of months.Today I went to sail and the upper transom rudder fitting was separated from the hull.  Questions are:1) What are the appropriate bolt sizes? 2) What, exactly, are the bolts screwing in to?  In other words - I see from the outside - the four holes for the fitting - but I'm concerned that the 'female' part - where the bolt goes in - might be stripped out.  This is why I'm wondering what the bolts might be screwing in to.Any further detail on this topic would be greatly appreciated.Thanks.pb

The rudder fittings are bolted through the transom on my Douglass.

There are stainless steel nuts visible inside the boat.

Phil Scheetz
FS 4086

Thanks Phil.If that's the case, this is an easy fix.Do you know the specific size of the bolts? 

No, but the other fitting has bolts that you could take one out and bring to the hardware store. Otherwise call Harry and order from him.