sweet mercy!!! a heating element, and cable. and want 350 bucks? someone has highway robbery written on it!
there is some aftermarket / 3rd party companies that make a large amount of "block heaters" for all sort of tractors / vehicles / machinery. it has been to long for me to remember names. since i went a search for my own tractors. i want to say ran between 20 to 60 bucks. but that has been 4 to 6 years ago.
google keywords
engine block heater
block heater
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there are some inline heaters, that connect between radiator and engine. they have a heater element inside and a pump. but these tend a bit more, and can be rather difficult to find a place to actually mount them correctly, without them getting torn off. they cost a little more than a generic block heater (hoses, some fittings, and over pump cost mainly added to the price over block heaters)
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just double check myself with google, i would want to know how in the world they can ask 300 plus bucks for a heating element and cable!