Tom,
I would start by going to salvage yards for bus parts. Radiator shutters actually are very beneficial in that they save fuel. If when they close virtually no air passes through the radiator and it reduces the load imposed by the fan. Lore has it that the radiator fan can take as much as 30 HP but I have no verification of that.
If you want to see how something that blocks air flow can reduce the load on a fan, run a vacuum cleaner with nothing impeding the air flow into the hose. Then stick your hand over the end of the hose and you will immediately notice the speed of the vacuum motor increases since the load has been reduced.
Jon and Di 2006 Liberty Elegant Lady, 2021
Jeep Grand Cherokee, 1950 Ford
Knoxville, TN
Owner of three Liberty Coaches since 1990