I’m not positive the overflow exists, all I know is when I tried to add the specified amount of fluid with out filling the torque converter part-way through I would end up with a mess.

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1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

1986 560SL - Wife's red speed machine