Have an '01 3/4 with an automatic that I rebuilt the engine and ran across something if I can get some help with. The AC compressor bracket is also where the lower radiator hose connects and then bolts to the block and has a water jacket. Looking at it, it looks like it may take a gasket inside it. Does anyone know for sure and if so know what the name of it is?

 

It's a water inlet O ring. The Cummins part # is 3906697