We sell the HeaterCraft brand, and I've been very happy with it. Since I'm not a diesel trawler yet, just a little 5.7(350) Chevy, I also installed an auxiliary pump to keep the hot water going to the heater box behind the mid cabin bulkhead.
I removed this panel and installed the HeaterCraft 4 vent in there. I also added a 120VAC and 12VDC outlet on this panel along with one of the 4 vents.
A three speed switch was mounted on the helm to regulate the fan speed and another by it for the pump.