Sorry Don, my error! (I've corrected my previous post to prevent any further misunderstanding!)
The MC21 HRC delimiter has two grey plugs (the only delimiter with 2 grey plugs!) that need to be cut off, and the wires 'spliced' into corresponding wires on the harness. This means you will also need to cut the black connector off the standard harness. The Black connector on the HRC unit then plugs into the PGM.
In the interests of resale, or the unlikely event that the HRC unit is damaged, make sure you cut into the stock harness far enough back that you can easily re-splice the standard black plug back in if you need to.
What you have does indeed sound like an MC21 HRC delimiter. E-mail me a picture if you can and I'll tell you for sure.
Andy.
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