Back to the Idea of Block heaters...
The stock block heater in my '80 300SD recently reached the end of it's service life and I've been researching the whole block heater thing for a couple of weeks now. I tried to remove the old heater but that was impossible (broke 2 wrenches, luckly craftsman). I installed a cheap hose heater and that did not work due to the design of the thermostat in this car. FINALLY I went to the local NAPA auto parts and requested a heater for my model Benz and they handed me a catz heater which you remove the block coolant drain and T into an existing engine heater hose. This style of heater has worked the best out of any, even better than stock - set on a timer it will keep the engine at 160F and my car starts with a remote starter!
~ William