I've seen this line fail in the same place when there is no rubber cushion between the line and the clamp.
The simplest way to get going again is have the line brazed (hard soldered) with a sleeve around the pipe to stop the leak. A new line will be more costly and special order from the dealer.
Wrap it with a piece of thin rubber or better yet use an Adel (MS21919) type clamp so it won't rub and fail again.
Dieseldiehard
1971 220 (gas) 4-spd manual 106441
1979 300TD w/ ’85 turbo engine 295530
1983 300D 243280
1985 300TD 217300
1987 300D 258230

__________________
'95 E320 Wagon my favorite road car. '99 E300D wolf in sheeps body. '87 300D w/ Sportline suspension. No more '79 300TD w/ 617.952 engine at 367,750, it was my annual driver to Texas and I sure don't miss it poor A/C heater system!