I want to flush ATF by pulling off the return hose and running the
engine to squirt out the fluid from the torque converter.

Here is my question.
How do I know which is the return hose?

I did a trans service on Dodge Caravan last weekend. Dropping pan and
replacing filter went fine. After reinstallation of the pan, I went on
flushing.

I pulled off one of the hose at the trans case side, assuming it as the
return hose. Plugged the hole with a plastic thingy.Put the hose into a
big glass jar, set up a mirror to watch the hose and jar. Started the
engine and put the gear into D.

Bang~ What a disaster! It was a TOTAL MESS. The plugged hole was
actually a pressure pump line. The fluid banged out of the hole and hit
the radiator to my garage floor. End of story, so much for DIY.

Say, it took tremendous efforts to clean up my garage floor

A lesson learned, I don't want to make the same mistake. Anybody knows
how I can find the AFT return hose on Sonata-99 ?