8178, just a hint on O-rings. I had a need for some O-rings to rebuild the brake cylinders on my full sized airplane. Someone suggested a local hydraulic repair shop. In a little half run down building on a side street the man who ran this hydraulic equipment and hose repair shop had huge quantities of every imaginable O-ring. He even gave me a handful at no charge as he said they were only pennies a piece the way he bought them.