They physically are the same injector basically, so yes they would fit and run, however, the 240D is non turbo, so the injectors run @ 115bar, the
300TD is a turbo, so the injectors run at around 135bar, so they would need to be recalibrated to the higher pop pressure to work properly, otherwise they pop prematurely with less atomization, same effect as advancing the timing on the pump, only with less fuel burn. If you still have the corect/original injectors in each car, you should see a stamping on the side of them right by the part numbers, that reads what pop pressure they were originally set for.

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Chris
64 190D R.I.P.
80 240D W/617 engine -for sale
82 240D -for sale