transmission leaking into engine?

I have a 1995 aerostar that is using about a quart of transmission every 200 miles. I can't see where it is leaking underneath the van. The odd thing is that when I check the engine oil it's going up on the dipstick. It is getting clearer in color not darker. I'm not losing coolant so it's not a head gasket. How could the transmission fluid be going into the engine?
Any help would be apreaciated
Mike

The only way fluid can get into your engine is via the modulator. I don't think you have one being a 95. It would be on the passenger side of your transmission not far from the Cat. Converter. Usually when a modulator goes bad it goes into the intake and gets burned with the fuel. Check your vaccuum lines if they are swollen and really mushy then you have ATF getting sucked into the engine.

Turned out to be the modulator. My wifes uncle is into fords and had the same problem with a truck years ago.
Thanks for your help.
Mike