You needn't bother to replace the outer filter nor drop the pan.
Just drain the ATF (17mm plug), then reseal. Add 3.5-4qts max
ATF through the top dipstick hole (get a skinny funnel with a long
tube).
Cycle the tranny through P-R-N-D a few times then drive normally.
Any slippage should be completely resolved. (If you get REAR
end chatter than that's a different matter, requiring an additive to
super-lube the AWD transfer case bearings.)
If someone thought the trans was the motor and added 4.5qts
you're only slightly overfilled; since draining a partial amount is
difficult to measure easily, AND double-draining an old EAT4 is a
good idea if the fluid is dirty anyway, just drain it ALL and measure
the 3.5-4 going back in. If the drained fluid is super-clean you can
reuse it, but I wouldn't cheap out on ATF.
Under no circumstances back-flush the tranny to force-drain more
than 3.5-4 qts (it holds 8.8qts), as you'll push detritus into the
sensitive valve body. Got it?
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