Re: Those with 203 Thermostat
before i changed out my water pump i was running at the "O" and never moved above it. now that i changed the pump and the t-stat it runs at the "M". and yes, the stock '95 t-stat is a 203* t-stat. i found that out when i asked this same question after i did my water pump swap.
1995 F-250 SC 2wd zf-5