For many years, my grandfather lived in the town of West Jefferson, NC, which is home to an old, independent bottling plant by the name of West Jefferson Dr. Pepper.
They make bulk fountain drinks, but also bottle a lot of older brands in glass bottles(and their glass bottle drinks are made with cane sugar). Aside from Dr. Pepper, they also do RC, Nehi, and Sunkist. I think they also do Cheerwine, but I've never seen bottle caps with their name on them. Of note, though, is that they also bottle Mt. Dew. Their Mt. Dew franchise ownership predates the brand being owned by Pepsi and consequently they are able to still bottle it despite being owned by Dr. Pepper.
West Jefferson is really careful about selling Dr. Pepper and Mt. Dew outside their distribution area, so you're not likely to find it outside northwest NC/southwest VA/far east TN. For that reason, they're not as well known as Dublin Dr. Pepper. Still, though, speciality soda shops or sections in stores have become a "thing" in the last few years, and if you browse one and pick up a glass bottle of RC, Sunkist or Nehi the cap will likely be marked for them.