There is a company called Scosche. They make numerous wiring harness adapters that will adapt your original dash harness to just about any and every aftermarket radio.
The harness that is supplied with your JVC probably has a plug that plugs into the radio. The Scosche harness adapter, which are vehicle specific, plugs into your original Ranger plug.
The wireing diagram that will come with the Scosche adapter will have the correct wiring colors so it's just a simple matter of connecting the wires.
You do not, should not cut your factory plug...there is no need too.
Been using Scosche products over last 25 years and have never had a problem,
You can also, as mentioned, check Crutchfield as they also carry vehicle specific adapter plug/wire sets.
This is a photo of the Crutchfield Metra harness adapter. It will plug into the factory harness. You then use the plug that came with the JVC, and simply connect the wires. Wire color is pretty much universal new, even between makes.