Transmission fluid questions.
Oh man, I really kicked a bee hive here. Didn't I?
Been around to see that exact bee hive kicked a bunch of times.:D
The truth is you could literally use canola oil as already mentioned, so any standard Dexron type ATF will be just fine.
BTW, some converters have a drain plug and some don't, so the ones that do can be drained.
Refilling procedure is the same mostly, but I prefer to pour in about 4 quarts before ever starting it so it has plenty to refill the converter right away.
Then finish filling with it running.
Unless you have the modified manual valve in the trans you want to check it running in neutral.