convertor seal leak

Hey Ash it sounds like you had it filled correctly. Not sure why it leaked as I have not had any problems with any I've rebuilt leaking and some have went in some pretty quick cars. I wonder if your converter may have a small crack in it somewhere? Saw that happen on one that would leak then stopped then started again. You are correct about the vent's location. I have read about the mod to tap and plug the vent hole (takes a 1/8" pipe tap and plug) and tried it once. Didn't put the vent in the main case though, put in in the tailshaft according to what it shows in Munroe's 727 Torqueflite manual and the dang thing slung fluid everywhere. Looking at it closer I see where he showed it should be puts it right close to the parking brake gear and I think it was acting like a oil slinger. I thought about trying it farther back on the extension housing (you can put it just about anywhere and it'll do the job) but needed the project done so I just plugged it and opened up the factory plug and it was fine and still working fine 5 yrs. and nearly 10,000 miles later. Never leaks a drop.