What the title says. Does fluid move between the two? Because my transfercase was filled past the fill plug even with a leaky rear output shaft seal, and my transmission is low. I mean I guess it does I just had no idea... The seal is brand new so I got a Repair Sleeve from National can't remember the part # but it was about 40 bucks for a thin metal ring and an installer cup, how does this thing go on? thanks.