1969 Orange Houndstooth Material, Is this NOS, bought in 1989 from C.A.R.S.

[1969camarors427]

I have some orange houndstooth material that is suppose to be NOS. It was purchased many years ago (pretty sure it was 1989) from C.A.R.S in Michigan.
I was told that C.A.R.S. had bought the remaining material from GM and was selling it. A local guy had bought this right around 1989 from them and it is still in the original box that it was sent in.
Does anyone know how to tell if it is GM material or a reproduction. There is suppose to be a difference in the pattern on many of the reproduction materials sold throughout the years.
I have quite a large piece, around 54 square feet but I have not unfolded it to check.
Let me know your thoughts. Thanks.