Parts Geek - For 1955-1956, 1958-1959 GMC PM250 Thermostat 16735HF. 1956 GMC PM250 5.2L V8. 1955 GMC PM250 4.7L V8. 1958-1959 GMC PM250 5.5L V8. Notes: Fail-Safe -- The patented Fail-Safe (R) thermostat is the only thermostat on the market designed to lock in the open position, allowing coolant to continue to flow in the event of overheating.; Temperature 180F.
