86590117 is the New Holland part number for the block heater kit. Should be in stock and under $30 at any NH dealer in cold country. Kit comes with very good instructions, not a bad job. Or you can match one up at an auto parts store that might fit, pay nearly as much (if not more), and figure out how to do it on your own.
Every tractor that leaves our dealership has a block heater installed at predelivery, unless the buyer specifically opts out. That hardly ever happens.