transfusion of transmission

Sharpz · March 21, 2021

I know this has been covered, but before I attempt to tackle this (first time doing this) I was hoping someone has done this before, and can offer up some advice. I know flushing the transmission is a bad idea in most cases so that wont happen. What I am looking to do is the method of disconnecting the top tranny line on my radiator, inserting a fitting with clear hose to push out the old until I see the new, by adding new to the dipstick fill . I also plan on doing a trans filter replacement. So what my questions are

1) does anyone know what size fitting I need to insert in place of the top tranny line, and what thread type it is.

2) what is the procedure for exactly how to get the fluid pushed out. Ie does the truck have to be running, moving through gears or can it be shut off and just add fluid until it is clear? Also I understand this will remove the old fluid from the line/s themselves but should i also have the drain plug removed while I am doing this or should it be closed until I see good tranny fluid?

3) do I drain the tranny pan first, or should I wait till I get the line/s cycled out?

4)Lastly is ATF VI the one i should be using (2004 gmc sierra 5.3 4x4) and what brand filter should be put in this truck)

Any help of detail instructions would be appreciated. I am trying this for the first time, because I think when I take the truck to the dealership, they only drain and change the filter in the pan. I dont think they do anything with the lines. They also told me I was good for 100k at the last change, but I read somewhere that it should be 50k.