When you look for that top breather unit...
For those reading this and need to know what it looks like when it's removed...
As described, it is a simple 90 degree cap and seal to insert a tube into the chamber the gears turn and churn the oil in. This is where the expansion and any foaming - will fill into this tube and up the hose into a little container - it is hollow and can take fluid - so this may be where people inadvertently put too much oil into the transmission - damaging it.