Leaking Oil Line: 1994 2500 w/ 7.4L

I had the lower (?) oil cooler line replaced about 2 years ago (at a very high cost) and now the bugger is leaking again. In going through on line part catalogs and my Chilton, I cannot find a Delco part # or the name to look it up by so that I can replace it.

What is this thing called? It is basically a hydraulic line attached to some large diameter silver tubing (like maybe 1/2") and goes into the radiator from the block. I remember the part wasn't cheap.

Thanks

Well I found one of the lines, now I need the other. I did find a number on the line: 5001353

Any help is MUCH appreciated.