A903 leaks like a stuck pig

OK- so last year I discovered my transmission was low, real low of fluid. I added fluid, and it was like a water works laving a trail wherever I went. I pulled the transmission, got a rebuild kit from onlinetransmissions.com and replaced all the seals etc. everything looked very very good, the 2nd gear syncro looked good, the input shaft showed almost no wear. So I just replaced the seals and put it back in. My FSM say 6 pints of Dexron, so I tried to fill it to that level. I could only get about 4.5 pints in so I ran it like that. It immediately started leaking like mad again, so I just drove it for the rest of the season. Now I’m going to figure it out and fix it! I know guys like @RustyRatRod or @AJ/FormS have extensive knowledge of the old A903, where do you think I should start looking first? And is it possible that the 6 pint fill is a typo and what I am really doing is massively overfilling it? Ohhhhh, A903 behind a 198 /slant in a 70 Duster…..
Cheers
Tim