Which thermostat to use?

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2004 Evinrude 225HO
Model-E225FHXSRS
Serial-05068373

Awhile back, I was having problems with my motor fowling out sparkplugs. I went exclusively to XD100 oil and the Iridium(Sp?) sparkplugs. Things seem to be better, but I still have to replace sparkplugs at approx. 100-110 gallons of gas. Seahorse told me I should go with the newer ETEC thermostats in my engine. My questions is, what is the part number for the thermostat that I should go with?

Thanks for the help as always, Brad

[SEAHORSE]

#5005440

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Thank you!!!!!!!!!!