A very basic point Billy, in the line of globe collecting, is that almost all one piece globes were originally produced from 1931 and before. (generic Shell clams and most Standard crowns are not in the rare category like most of the 1931 and before one piece globes)
The Pegasus logo, used in conjunction with the Mobilgas name and design as depicted on this JUNK globe in question, dates to 1934. I think these two basic points are enough to make an informed decision on this globe.
Socony-Vacuum was a very large company, making the Mobilgas and Mobilgas Special globes some of the most plentiful and commonly available in the hobby. I would readily make a bet that if this globe design was ever originally produced in the early 1930's, it would certainly be documented and several examples would probably exist in the collections of well known rare globe collectors today, which it does not.