Hi all,
I know this thread hasn't been active in some time, but I found something that (might) be relevant so I thought I would share. I had read the discussions about the tape wrapped around the heater blower motors and whilst restoring mine (66 GT350), I found some of the tape inside the motor. It was used to wrap around the soldering that joined the wires to the winding.
It fits the description that people posted so I assume it is the same tape. As it was inside the casing, it hadn't faded. It peeled off cleanly and you can even see the perforated edge (like a tape dispenser). The outside had blackened a little, but the color is definitely a light brown similar to masking tape but a little darker. Its quite rough textured.
The attached picks are taken in as best to natural light as I could get for the color. The underside (shiny in the pic) is still very tacky and sticky.
Hope this is of use.
Cheers
Stan