Originally posted by gidpor
...which recently began running a little hot,(no redline...)
This part concerns me. If it used to behave properly with an 87C thermostat then the problem won't be fixed but might be masked by a 71C thermostat. In 15 years you'll be looking for a 55C thermostat
The thermostat regulates coolant flow through the engine but it's not an open and shut deal (no pun intended) as someone pointed out so a thermostat of a different rating will likely change the temperature characteristics of the engine. This isn't an MB phenomenon, it's true for many engines.
Just because Behr makes the thermostat doesn't mean it belongs in a particular car. The Behr radiator cap for an 85 300SD is different from the Behr radiator cap for an 87 300SDL. But they physically interchange. If MB said that you should use a 71C thermostat then a phone call to your MB dealership should confirm it. Was your car originally destined for local (Singapore?)delivery?