This same question came up about 2 weeks ago in the context of a
B2150 on another thread. Block heaters are just a source of trouble in my opinion. There are all sorts of issues including leakage, limited area of heat, etc. Heat does not get distributed well from making one spot on the side of the engine hot !! I have used the lower radiator hose circulation type heater in VW diesels starting back in 1979. They work great. Advantages include warming up the whole relevant area at the same time (engine, radiator, starter motor.) They also work faster and can be used when you have a shorter amount of time prior to wanting to start the engine. I recommend using the in-line heater for sure if you can find space to put it.