It's Cold, Please Help
 

I want to get an engine heater for my '79 since it has trouble starting in the really cold. It has a 85 straight 6 in it and I know nothing about engines or the like, what should I look for/get?

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Kat's Heaters Handi-Heat Magnetic Engine Oil Heater - 200 Watt Kats Heaters Vehicle Heaters KH1153