A/T vaccuam modulator leaking will suck in ATF and burn it . no leakage puddles yet a oil loss

Thanks. How can I check whether this is the case with my car? The vacuum line from the vacuum modulator on the transmission to the vacuum control valve right behind the injection pump is white. If I disconnect that vacuum line from the vacuum control valve and do not see any red color stain on it, can I conclude that my ATF is not going into the engine?

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1992 300D 2.5 turbo diesel. 319 k miles.
124.128 chassis, 602.962 engine, 722.418 tranny.

Friend, remove the plastic underwear below the engine and transmission. Park the car over a fresh piece of cardboard large enough to cover the floor area under the engine and trans where it is parked. This test will help determine the severity and general location of the suspected trans leakage. The plastic underwear on the diesel is as absorbent as Benz-Depends and may hide the leak.