If you don't drop the pan, you can't clean or replace the screen inside,
where most of the debris accumulates, and a pump won't get all the old fluid
out.
If you were trying to drain the filthy water out of a toilet, you wouldn't
just bail it out with a teacup until you couldn't reach the bottom, would
you?   It's my view that any vacuum device that sucks fluid out of a
crankcase or a transmission is a half-assed way of completely getting rid of
the old oil or fluid.
comments?

=======================
Transmission fluid can be drained from the drain plug already included
in the pan.
You need a 10mm Allen head socket.
Good idea to measure the fluid removed so you can add back correct
amount.
Make final level check after driving at least 10 miles, idling in Park,
after shifting through the gears.

I bought mine at Sears. Saw the same one at KMart. Make sure it comes
with the skinny black tube to fit down the trans filler tube. Some
don't.