To remove factory cooler, hold front of tranny up with a jack.
unbolt the 4 bolts that hold the tranny mount to the frame (and the
ground strap).

Carefully lower the jack a few inches, then you'll have room to work.
Don't forget to clamp the water hoses while you disconnect them so
you don't spill coolant in your eyes.

If your water/oil cooler has been breached, use a separate air cooled
unit (and flush the tranny fluid a couple of times).

Below is a $150 kit from Smallcar.com with the appropriate fittings.
Many subaru folks use this solution.
auto tranny cooler kit http://www.TinyURL.com/o4opa

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You can also buy the cooler by itself separately from
http://www.cip1.com for $68.50.

If you have a hydraulic supply place near you you may be able to get
the fittings along with the metric adaptor as shown below, the metric
adaptor can be hard to find, so bring in the bolt from your original
cooler for comparison:

http://www.californiavan.com/subaru/autotranny/coolerfitting.jpg

>I recently realized coolant is getting into the automatic
>transmission and transmission fluid into the cooling system. The
>first hint I had that anything was amiss was when the transmission
>hesitated to go into gear from a stop, then lurched into first when
>I gave it more gas. Maybe I should have had it towed, but I drove it
>12 miles to home and it shifted normally at freeway speed. I stopped
>driving it after that and checked the transmission fluid. I
>immediately noticed the color wasn't right. It was a milky white
>pink color, somewhat foamy, and the level was considerably higher
>than it should be.