Transmission losing oil

[krjt]

I have a 89 300E and just recently it started to lose transmission oil. It does drip a little, but not at the rate it is disappearing.

Is there a vacuum modulator in these transmission where the vacuum rubber ruptures and gets sucked into the intake manifold?

I plan on checking the plugs this weekend for oil and the antifreeze too.

Any thing else I should look into?