I have a 2006 ford focus ZX5 and I want to replace my OEM speaker with an aftermarket one, but I didn't realize that I need an speaker harness adapter until I removed the door panel. The speaker I bought just has two wires, but the OEM speaker actually has a plug. What kind of speaker harness adapter do I need to connect the aftermarket speakers? I looked up on rockauto but I just found some speaker connector that costs $40, I hope that's not what I need.