I'm surprised that your Stealth have stainless fasteners there. I remember Wayne fixing his rudder at Grafham last year, and his were brass. I'm fairly sure mine are not stainless either.
Maybe it's a generation thing and John ran out of brass screw

BTW if you can't find those fittings stateside, send me a PM: I can buy one locally an send it to you. the Datchet shop have those in stock (or can order a two days delivery)
The seasure catalog is there:
http://www.sea-sure.co.uk/05indexb.html those are on page 5, in the first PDF.