I'm connecting a trans cooler and would like to extend the hard line to the cooler with additional hard line. I got some 5/16 line, but need either a connector or ferule or something. The male of the extension fits the female of the existing line. I tried a 5/16 ferule, but that didn't work. In the past I've used a short rubber line with 2 clamps to connect them but this time I'd like to keep it all hard line. Anyone know how to do this?