I have a 4R70W, which I want to drain the converter fluid, Stupid qestion, how does it get refilled?

 

The pump in the transmission will fill it from fluid in the pan.

Mark

 

If draining the Converter and pan, after its buttoned up, put in about half of the total fluid it will need, and run it in Park for 15 seconds or so. This will re-fill the Converter, and make space in the trans case for all the quarts yet to come. Forgetting this can cause some of those quarts to have no place to go, and exit via the case vent!