help with factory oil guage hookup and line

[arcticman]

Hello everyone, Can someone tell me if the factory oil guage had a sending unit or was it connected directly to an oil port on the engine side. Im changing out my insturment cluster with idiot lights for one with actual guages the temp and alt. guage are not an issue but im not sure how to connect the oil up. Im thinking they used copper line with compression fitting and went dirrectly from the block to the guage. I know newer aftermarket guages use a plastic line instead of copper. where would i get the line and fitting?
thanks Scott