As per what
@MAY03LT said:
That's why the pan was almost empty.
I got 4 qts out with the hose and there was 1 qt left in the pan. The whole flush used 14 qts.
I can't find a post that's actually about flushing the transmission following the video @MAY03LT made.
I just finished doing it myself and boy was that ever easy. I did have someone to start and stop the engine for me. I would like to add a few tips.
#1 You'll need 3 catch pans. One to pump the old fluid into, I used an all purpose 5 Gal utility bucket from Home Depot. It worked great because it also measures fluid quantity.
You also need one to leave under the tranny cooler where you disconnected the line because it will drip quite fast the entire time and one to put under the dripping transmission while the pan is off..
#2 Bailing wire is your best freind! I used it to hold the hose end up while doing the filter and again to hold it in place when pumping the fluid out while at the same time pouring more in.

#3 Buy gallon jugs of fluid, not qts. I bought 4 and have 1/2 gal left over.
Note: Yes my garage is carpeted with no padding underneath. Working under your vehicle laying on pile carpet is awsome. I have a nice creeper that rolls on the carpet just fine but I don't use it unless I'm sliding in and out a lot, like when I dropped the fuel tank.
Also, my adult daughter who normally parks in the garage likes to drive home from work barefoot and with the carpet, which I vacuum regularly, she can walk into the house without putting her shoes back on.