My old 12v Cummins trucks always have a factory block heater. I've been looking around and cannot find one on the 300D. If installed, where would it be hiding? It appears from the link below that they were available.

https://www.*******.com/products/mercedes-block-heater-kit-q6200009



Were they a customer option versus automatically installed? My car came from California so it may not have had one if it was an option. Here in Ohio, it would be handy. Thanks!