I'm a week or so late on this post, but thought I would give you this link if you have any more inquiries/questions regarding old soda bottles. And as already ascertained, your Dr. Pepper is fairly common, but is still a "Keeper." The Dr. Pepper to look for is the painted label one with a big soda bottle "cap" on it. In excellent shape it sells for big bucks on eBay.
www.gono.comJust click on the "Soda and Beer Collector's Pad," then scroll to the yellow highlighted area of interest.
Good luck, and thanks for sharing.
SODABOTTLEBOB