do you mean the clip on piece on the end of the fuel line where it meets the fuel rail??
If so they are pretty common, i seen them on fiats, vauxhalls, alfas and vw's. But no idea where to get them, when i got my engine i cut a bit of that pipe off so i had the connectors. From memory the return is slightly different too.
I think, but don't hold me to this, if you went to a scrappy and cut the 2 fittings from either side of the fuel filter on a spi cinq/sei or mk1 punto they are the same, there is probably more cars that will have suitable connectors though. But they have 2 push in tabs on either side you have to push in to get them to pull off and they can be a right hassle to get off.