in a 1984 ford150 truck, where is the block heater

well there are a couple of types...none are factory...there is one type that goes into one of the coolant lines and plugs into the wall, there's another type that goes into the dipstick tube and keeps the oil warm...all aftermarket products...if you could give me the name of the block heater you had in mind I could sniff out the paperwork for you~

here are a few choices from GOOGLE~

If it had one installed from the factory, it would be in a freeze plug on the side of the block.

but an electric receptacle plug to plug from there?....hmmmm will have to think about that one.~