I use the "Right Stuff " sealer on all my tranny pans, never even a hint of a leak.The one in my truck was done 3 years ago and my dart was over 4 years ago.Unlike silicone and most other sealers tranny fluid doesn't bother the Right stuff
I gotta get some of that, I've gone through almost 4 gaskets now trying to get my 904 to stop leaking. I think the pan is still a little warped or bent slightly.
BTW what's the proper tightening sequence, if there is one?