Thanks! It's the nylon fuel line that attaches to the stainless fuel rail that feeds the fuel injectors. I'm not sure if it's the send or return, but it's the upper one. The Caddy dealers no longer sell the nylon fuel line assembly. I found this out when the fuel line at the other end where it attaches to the fuel pump was leaking. I was able to buy a GM connector that connected/snapped on to the fuel pump fitting with about two feet of nylon attached to it at the auto parts store. I attached that to the fuel pump fitting and cut the old one off about 2 feet in and reattached the new piece with a quick connect fitting at the cut . You just slide each end of the fuel line in each end of the quick connect and they lock in place. It's been on for a couple of years with no issues. It was either that, or buy rubber line and run it over to the fuel filter. I was hoping to be able to do something similar up front. I thought about cutting the nylon line and slipping a piece of heat shrink up over the pin hole leak and then reattach the line with a quick connect, but I'm not sure if the gas from the pin hole will eat through the heat shrink. Thoughts? Thanks again!