6.67 is the same ratio of the gearset used in my CCKW (G-508). The one in your images looks a lot like the gearset used in the corporate (aka "banjo") axle used in some G-508s and all G-506s.*
The odd part is the "Studebaker" reference on the box. The Army's 2-1/2 ton Studebaker US-6 used a different driveline, which was made by Timken and was of a totally different design. The ring and pinion sets are not interchangeable.
Best Regards...
*Edit.
After looking closely at the TM, this is not true.
Ring gear on the corporate axle has a wide shoulder on it, to provide contact area for the thrust block. The ring gear in your image does not have this feature. Sorry for any confusion this might have caused...
