Dan,
You're welcome.
I already mentioned this to you but I'll repeat it here for other readers.
The 101.07301 pictured above has had two modifications done to the countershaft assembly, the component parts of which appear to mostly be from a standard 101.07301, The hanger assembly has been disassembled and turned around (except for the 4-step pulley driving the spindle) so that the motor driven pulley is on the right instead of the left. That allowed the owner to mount the motor behind the bed instead of sticking out to the left of the headstock. Frankly, I don't know why Atlas didn't do that to begin with. It makes for a smaller footprint.
It also has a 4-step motor and motor driven pulley instead of the standard 2-step ones. This makes it a 32 speed machine, not a 16 speed one. Almost all of the Atlas 6", 10" and 12" lathes (except for those that were sold without back gears and some that Sears sold as wood lathes) are 16-speed machines. 2 (motor pulley) times 4 (spindle pulley) times 2 (back gears).
The Atlas 9" and 6" that were sold by Sears before 1957 all had different legs on them from the equivalent models that were sold directly by Atlas. No one that I know of knows why. The 6" also had a different countershaft assembly, reason also unknown.
There is a lot of misinformation about the Atlas 6" models scattered around the Internet. I assume it is from lack of knowledge rather than deliberate disinformation. The most common two are:
Early Atlas 618's had 1"-8 spindle nose threads - False. There is no catalog or credible physical evidence to support this.
Some Atlas 618's had babbit bearings - False. Same reason.
Atlas built some of the 6" lathes sold with Sears model numbers beginning with 109 - False. If they had, the model numbers would have begun with 101 and the parts would look like Atlas parts.
All 6x18 lathes are called "618" - False. "618" is an Atlas Model Number derived, like 918, from the size of the lathe. No one else used it.
I don't have or have copies of all of the Atlas catalogs ever published, but probably have as many as anyone else on the planet. I do have copies or originals of every Sears Power Tools catalog published between 1931 and 1983.