It varies depending on the tractor. There are various sizes of lower radiator hose heaters available to fit. You should pull the hose off and measure its internal diameter...but allow for any flaring of the hose end. You might also want to do an on line search for installation instructions. Some of them must be installed in the hose so the heating element is always submerged, in which case you'd want to make sure your hose has such a place. My MF 1010 didn't.