What about aftermarket block heaters all the type that replace the
dipstick? Don't tell me google is my friend. I want you to do the work for
me. :-)

For what engine? All of the international diesels come with the heater
installed from the factory (05 and newer ford trucks do not come with the
cord but they can be had from International or eBay). I would imagine the
GM and Cummins engines also come equip. If you are sure yours doesn't then
you can get one that will install into one of the freeze plug holes. Just
pick a side and install it into the center hole. I am not a fan of the
dipstick heaters because they have been known to coke the oil that is in
contact with the heater. You can also install one of the heaters that
install onto one of the coolant lines. They apparently work well and also
circulate the warm coolant through out the engine. Another option is to use
a heating pad that glues to the bottom of the oil pan (and battery if you
like). They also work fine but can also coke the oil. There are tons of
options but I prefer the ones that install into the coolant passage. These
also work fine for gasoline engines, tractor engines and so on. All you
need is the size of the freeze plug to get the correct size heater.

good luck,
mark