When I go to get a thermostat for an engine and they have different temperature ratings, I usually put in the lowest rated one. I'm not sure if that is the right thing to do. How do you decide which is the right one and why do they offer different ones? Does it depend on what climate you are in or how the machine will be used? The engine currently in question is a CAT 3406B in a truck.
One thing to consider is engine fan clutch thermal switch. Back in those years it was very common to find that was a 205* switch. Fans didn't engage till 205* was reached. Most any I found I would replace with a 195* or 200* switch and normally install a 185*/190* stat with 195* switch and a 195* stat with a 200* switch. So the flow is wide open before switch temp. I do the same with Cummins.
That sounds like a good idea. I hadn't thought about that.