How much transmission fluid is in the A/T cooler when it is cold?

[keystone]

I had transmission fluid changed a few months ago by a mechanic. But last 4 years I have a leaking transmission cooler (very very little that mechanic said it was probably okay not to change it now). Since it has been 10 years since my radiator was changed, I am changing the radiator myself and while I am doing that I thought I should change the transmission cooler. Before ordering ACM brand A/T cooler, which is about $230, I have a second thought since I don't want to lose much transmission fluid that hurts the transmission (not more than the amount that would leak in another 30K miles or until next transmission service). If the front of the car is on the ramp-about 10 inches higher, how much transmission fluid, do you think, I would lose while putting a new one (whatever amount is inside the old cooler plus any comes out from the hoses)? When the car is cold, does the transmission fluid drains to the pan so that there is not much fluid in the cooler? I have 95 525 auto.