I wouldn't worry too much about overfiling it
as long as you are sure you checked it properly, like say after a 20 mile trip, while the engine is idleing, as the fans kick on, it don't get much hoter than that, on average here most members, claim close to 4 qts, no more, I did mine twice recently once after it sat for 8 months, and a week later, when it sat for a couple days, long storry, both times I got 5.5 qts out, took the same to properly refill, diference I my van has the towing package to the best of my knowledge, it has an extra tranny cooler, small, but overall, I used almoast 2 qts more than average, looking inside the radiator cap looks like that cooler couls hold a bit, maybe it is the way I do it it siphoned out where most members, did not, maybe the larger coolers, botom line if you checked it, properly and got good eyes, to me it was a bit hard to see it, and I have good eyes, 5.5 qts filled it to the top of the hot, just shy of the last hole, and I checked it several times, even measured what I got out, add a larger cooler to the situation, you need 6.5qts, maybe you overfilled half, disconect the return line and drain it, or leave it sience you are leaking allready, oh yes I do vote for the black rtv, had a **** of a time getng it off the second time, had all the bolts loose and it would not leak, tried prying it with a screw driver, no luck, took a hammer and a very sharp chissel to get it started, this is the first tranny I did without a filter, I asked the dealer they do not cary one. it was made for rtv