Transmission Fluid Mystery

I have a 91 Grand voyager and it seems to be loosing transmission fluid somewhere but no puddles anywhere.It looses between 3/4 and 1 quart a month an shifts fine.
Where could this be escaping at as I drive it?
What do I need to look at since its not dripping anywhere an I snugged the pan an didn't see it there?
Thanks

Assuming you have an automatic. Do you have a stand alone trans oil cooler or part of radiator? I would be checking cooling fluid and tranny fluid see if they mixed. If so, stop driving it. You will damage your tranny.

Antifreeze is fine.Yes it has a trans cooler beside the radiator. An is Automatic.

Still leaking.I'm going to change the pan gasket .would changing filter be a good idea with 175k miles on it ,an using same fluid(its slowly been replaced with over 5 quarts of added fluids over last 6 months )?...
I've heard of problems after changing old fluids an filter .

What else should I look at or tighten when pan is off and im under it..maybe shift solenoids?