When dealing with Shelbys it's hard to separate where the Ford part starts and the Shelby part begins. I wasn't too clear on that so I'll add to the discussion.
For those not aware, in 67 Shelby workers lopped off the Ford plugins for the Ford tail lights and added Cougar sections for the 3 bulbs in each Cougar light assembly.
So the front half of a complete "Shelby rear harness" is all Ford (including the braiding) and the rear portions are Shelby.
The vendor I mentioned, Lectric Limited, offers many different harnesses for 67 Mustangs. Quite a few I have not seen offered before.
They offer a complete Mustang rear harness (with braid) and it comes with Mustang tail light plugs.
But for a bit less they offer a Ford rear harness (with braid), but they don't include the Ford Mustang tail light plugs. They end the wire without any plug. The link in my previous post is to that harness.
This last harness assumes you have a good Shelby (Cougar) end assembly at home and just wish to replace the Ford portion of the harness. Since I have a Mustang harness with frayed braid and the Shelby ends are intact, this suites my needs perfectly.
I didn't know about the reproduction Shelby harness, so for those that need both sides of the harness, pay heed to Bob's warning.