GM never offered the all black impact strips. The replacement has always had the white stripe. You can remove the stripe rather easily with acetone and other paint removal chemicals. Done properlly no one will ever notice. New strips are still available from GM and the vendors.
I have one for $50+shipping, I took it off a car many years ago. I can take pictures of it if your still looking, its been in storage for about 15 years. Let me know if your still looking.