Have to agree with Oldsub on that. Nobody worried about a single-master system before duals came around. IMHO, the original system will be fine, IF it's gone through carefully and kept in decent shape. AND, have a parking/emergency brake you can trust if the worst happens. I'd get the Hydro working (assuming it has - or had - one!) and rebuild the existing system.
That being said, I agree that if this is a daily long-hauler, a dual system is relatively cheap peace of mind.
-Mike S.
