i had a 3550 leaking
oil out the front seal and between the main pieces. when i took the pipe fill plug out it made a sound like it was air tight. i guess the top breather was jammed against the panels up top. so i drilled a hole in the fill plug then put a wire in it so it wouldn't leak too much, didn't work, leaked too much. next put a fitting on it and strung the 1/2" x 2 ft. line up over the tranny and it leaked as bad,
oil all over the tunnel and rear. so i drilled and tapped a hole on top of the shifter and put a drilled pipe plug in it with a rtv'd cap on top with a hole in the side to keep any water out. works this way, plus i can use it for a fill point. tranny doesn't leak now either,