Forgot! CHECK YOUR SEACOCKS!!!!
Grampians came from the factory with gate valves for seacocks. This is a bad thing. Take a look at them if they look like the same valve you use to turn on your garden hose, they need to be replaced with proper ball valved ones (lever handle). Mine were frozen solid (in the open position of course), and would have resulted in bad things would one of the hoses let loose. If you would like, I can send youa write up on how I replaced mine with the correct ones.
1971 Grampian 26