Trans dipstick

I added the 6.0 cooler in my 01 Superduty.....added about 1 1/2 qts. of Mercon V to bring it back up to normal.

Your level should be the same as before , between add and full, hot in park idling

As said above, the dipstick tells you how much oil is in the sump when the engine is running. After its running and everything is full of oil it should be between add and full, no more and no less.

I haven't over filled it. I was just wondering if the level would be different.

Not familiar with Fords but aren't you supposed to check fluid level with the engine running? Methinks a quart over in the sump is a quart over.

I don't think so. If you need to add extra fluid to fill a larger cooler, that fluid should stay in the cooler and thus your trans level should still read full at the old mark, it will just take more fluid to fill the entire system. Overfilling a transmission can lead to blown seals and "frothing" of the fluid that could come up through the filler tube and leak on the hot engine.