I have a maytag msd2756dew refrigerator that has a bad defrost thermostat. I have already tested it and removed it. The refrigerator had been working fine for years. In looking into replacing the part I saw that the defrost heater and thermostat are sold as one unit. However, it appears that years ago when we had a technician fix the frig they just replaced the thermostat because it doesn't look exactly like the OEM part. So I would like to just replace the thermostat and want to make sure I get the right one. The numbers on the thermostat are T-0-D, 37T01, AM, 611445, L55-20F, J0520, MEXICO. If I understand some of the numbers the thermostat opens at 55 degrees and closes at 35 degrees. However I have also seen that it closes at 20 degrees. I would appreciate your advice.