[John B] I have a 1994 Gulfstream SunSport Diesel Pusher. GMC 6.2 Turbo It overheats even in cool weather and on level ground even without towing if speeds exceed 65 mph. Needless to say it gets worse if I tow, go uphill or use it on hot days. Radiator, thermostat, guage accuracy and other obvious things have been checked. Using conventional 1:1 Afreeze and H20. Any one out there with experience with this vehicle or knowledge of such a problem with this machine?