I did not use the plastic valve unit now installed by Heartland. I used an all-brass valve and it did not have a panel with it. I made my own panel to fit the UDC space. The first challenge was tracing the plumbing and making the correct connections. The toughest challenge was making a leak-free connection to the existing gravity feed tube that is the fresh water fill. You will have to get creative to make the transition from smooth plumbing tube from the new valve to the existing spiral fill tube. I do like the idea of all input water functions being in one selector valve. You do keep the separate water heater bypass valve.
You may be able to buy the valve and panel Heartland uses from Heartland.
I need to correct my purchase source reference. Even though I talked to and ordered from Anderson Brass, the selling entity was Robo-Fit. They have a website.