First, there is no such designation as a "300TD-T". It's either a 300D diesel sedan, or a 300TD diesel station wagon. Both are "Turbo-Charged".
Second, the plastic upper tank is prone to breakage in all Mercedes with plastic and aluminum radiators. The upper hose connection is the most susceptible to breakage due to two factors. The first is over-tightening of the hose clamp, and the second cause is mechanics leaning into the engine compartment to do repairs...
The real culprit is the age and brittleness of the plastic, but the other two are the final "straw".
Depending upon your location, and the type of damage, you may get a local shop to do a repair.
Check out this thread:
Otherwise, call phil at PartsShop for a quote on a replacement radiator: 1-888-333-4642...