TH400 transmission question

Trying to locate drain back holes on the TH400. I replaced the trans and installed the MileMarker t-case rebuild w/the overdrive. After witch the tranny would spit fluid out of the fill tube whenever the tranny got hot. I've already changed the vaccume modulator and put in a new filter and o-rings. I've also done a vaccume check on the vent tube and it seems to be free of clogs. The only thing left that i havent checked is to see if the drain back holes are plugged but i dont know were they are. Any help would be much apreciated.