Database says: Carquest Thermostat #TS 258 has m22x1.5 threads closes at 192deg F and opens at 182deg F this thermostat fits the mounts on Fluidyne radiators SOBill Taylor sobill at aol.com **************************************Check out AOL's list of 2007's hottest products. (http://money.aol.com/special/hot-products-2007?NCID=aoltop00030000000001)