Sometimes the effort to install a block heater, especially when the engine is still in the truck, may seem a bit overwhelming for a younger, less-mechanically-experienced truck owner. I know it did for me 40-50 years ago. As an alternative, I have found that an applied oil-pan heater will provide equally good results without having to drain the coolant and going through the process of getting a freeze plug out. Then there is the danger of not getting the new plug heater installed correctly and having to deal with a coolant leak, resulting in performing the exercise over again.
An applied oil pan heater installed on the flat bottom of the 6.2 oil pan will constantly add BTUs to the lower end of the engine. This heat will percolate up into the engine and provide sufficient heat to assist cranking in cold weather without a freeze plug heater. In fact, I believe that an oil pan heater is actually a wiser choice than a freeze plug heater because, upon cranking, warmer more-viscous oil will flow through the oil pump and arrive at the bearing surfaces faster than thicker, colder oil.
My P400 engine arrived from GEP with a factory block heater installed. However while I was installing the bungs on the cast aluminum pan for the mechanical oil temperature gauge and pre-oiler pump pick-up, I went ahead and installed a Wolverine Model 16 oil pan heater from Zero-Start. I plan to wire the two heaters together so that one plug will activate both heaters. The pad came with a tube of high temperature silicone adhesive to seal around the edges to prevent road moisture from getting to the peel-and-stick pad adhesive. I had some of this left over so I used it to adhere the 110-volt pad wire to the side of the pan and up to the thermocouple bung, where I zip-tied it to prevent the weight of the wire from pulling it loose.
Hope this helps.
