I"ve been working on the cooling system for my IH 574 gas tractor. I believe I"ve solved the overheating problem by replacing the missing cooling shroud around the fan but found that the tractor had been running with no thermostat. Now that I"m able to keep it cool, I"d like to put in a 180 deg thermostat. Have found (and purchased) a 377156R91 thermostat which I believe is the correct part for my C-200 engine (sn 1342), but the retaining ring that holds the thermostat in place (377180R1) is really expensive (abt $45 for a spring ring). Has anyone had experience in replacing the original spring ring with a standard snap ring?