Yeah but have you ever owned a pre-1973 w115 or 114? None of the seals are the same as your 1980 w123. It's a question of primitive synthetic plastics, nylon and rubber compounds of Vintage MB oil seals that prohibits the use of modern dexron/mercon filled with strange additives that will eventually eat their way past the seals.

(edit: And hey Helga's owner, remember me? I'm the guy from couple years ago chompin at the bit to give the 1970 220D an excellent happy and loving home - if you ever decide to pass her on, please let me know.