You may want to try a Heat Houser if you get an open station (non-cab) tractor. If you look at the attached website there is a picture of an Oliver possibly a 1650 or 1550 with a Heat House on.  For some reason the picture is on the John Deere page. 

I have never used one of these heat housers but I have thought about getting one for winter use for feeding hay. then take the heat houser off for Spring, Summer and Fall use. 

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