700r4 trans leaking

[jayreb250]

my transmission appears to be pouring fluid out I can't tell for sure where its comming from it's either a little black bowl looking thing on the drivers side,at the back side of tansmission or where the housing bolts up, I think its going to the transfer case, I need to go look at it again. my qeustion is what is the little round black thing? if its not that I was told that seal for the housing is hard to find could I use silicon to seal it?