Made by South Bend and made for distribution by Sears as a lower-cost model. From the Practical Machinest web site we learn that this 10-inch lathe was reintroduced in the early 1920's along with the 9 and 11-inch lathes. The "J" serial numbers are the first improved second generation lathes and this 10-inch model was based on the catalog number 19 "Special 10": and first recorded with an "S" in the serial number - this might indicate that it was made for Sears
This model was, itself, an improved  first generation machine (Catalog No. 260) a 10-inch lathe that Sears sold as the "Expert". The model 26 did not have a tumble reverse mechanism to reverse the leadscrew but the second generation Model 19 did - and a 3/4" hole through the spindle.
Other data is that the first-generation 9-inch Model 24 was improved and became the second-generation Model 25.
In an old South Bend parts document the term "Junior" is used to describe these lathes - this being the earliest-known mention of these lower cost machines.