I am pretty certain the engine block heater is an extra cost option. So some used vehicles may or may not have it.
Also you only really need it for extreme sub zero temperatures. -20, -30+
Not positive but my 08 didn't come with one and my bro in-law who works for a GM dealer said it didn't come with one and here in MD I wouldn't need one.
According to the brochures I have, the heater is an option that you have to order on the side. If you bought it off of the lot it might have the heater installed but other wise your're looking to add one on.
I thought It all depends on which vehicle and which year and which packages the vehicle came with. In the past some vehicle packages it was standard with the diesel, some it was an option for certain vehicles built in certain years. There are base packages, LS packages, LT packages. So some vehicle builds that come with the diesel may have it standard and in that particular package the block heater is included. For other packages it may not be included. I believe NOW it is included standard with all Duramax diesels but in the past it was not standard and may not have even been available when the duramax first went into production.
GM has built all sorts of vehicles with all sorts of packages with standard and extra cost options over the years.
Every vehicle that GM built and got a diesel in the last 10-20+ years I don't think also got an engine block heater as a standard feature no cost option included with the vehicle.
I'm done with this..... I'm not arguing..... This is not what this thread was started for in the first place