I have a 1993 HR Navigator and previously owned a 1989 HR Imperial Class C with a Ford chassis.
Back in that time period, Holiday Rambler was a stand alone company that built very good RVs. Quality was evident in just about everything they did. One easy way to determine how careful HR was, is to check the weight limits against the actual weight. You'll probably find more capacity than most other rigs of that time frame. I would find it hard to believe that your coach was built to meet just minimum requirements.
All that being said, I can't remember exactly how many radiators my Class C had. I suspect your coach has a transmission cooler, an oil cooler, a air conditioning heat exchanger, and naturally the main radiator. If you're concerned, have a shop flush your cooling system, replace the main hoses, thermostat, and coolant.
