Hi.
First of all, your 1982 (that's what it says above "message") never had a TCB -- this started in 1985 or '86.

Second, the gauge only reflects your coolant temperature, and it's perfectly normal to fluctuate commensurate with driving conditions -- this means that there is not one "proper" place for the needle to lie. Such factors affecting driving conditions includes considering not only how hard the engine is working (including whether your A/C and/or heater is turned on -- the latter being an auxiliary radiator, in effect -- or whether you're driving at highway or urban speeds, etc.), but also considering (obviously) the ambient air temperature.

Third, there are three different possible thermostats for our 240s, and anyone (your mechanic, a previous owner, etc.) may have installed either of these -- and will influence where your needle rests under any of the aforementioned driving conditions. These thermostats are 87°C (p/n 273459-8), 89°C (I don't know the p/n), and 92° C (p/n 273307-9). If you live in a hot climate, or your car has marginal cooling, use the 87; if you have a later car, the hotter 92 thermostat is recommended for greater fuel efficiency.

So for all these considerations, it makes little sense to ask someone else where their needle lies -- it will be different for different cars driven in different places and different driving styles. As long as your car isn't overheating, things are good.

Regards,