Block heater is nice for pre-heating the engine so you get warm ate from the heater sooner. I have a 2001, I have used the block heater as a good neighbor tool when the temp drops below 40, as the engine on my 2001 doesn't sound like the bearings are falling out. I don't need it an have started as loaw as about zero F degrees, just with a single cycle of the grid heater.
Ram doesn't use glow plugs, instead has a "Heater Grid" that heats the incoming air stream before it gets to the cylinders. Like having an electric hair dryer in the air stream. Works very well for cold weather starts.