Mathew,
There is no such thing as a "101.2048". "2048" is the important or unchanging part of the Sears Catalog Number for the Atlas built 101.07301. Which is the 6x18 lathe with 1"-8 spindle nose threads and sleeve spindle bearings that Atlas built for Sears from 1939 through 1957 (catalog year). The characters shown in the catalogs prefixed to the 4-digit or five digit number (like 99 PM, 99 AM, etc. ) define some things like shipping requirements (i.e., Motor Freight only, etc.) and those codes sometimes changed over the years. But the all numeric part of the catalog number usually didn't change unless the model number also changed. It wasn't until sometime around the end of WW2 that Sears started using catalog numbers that partially matched the model numbers. This was not changed retroactively and the earliest Atlas machines that I know of that were done this way are 99 AM 2743 for the 101.27430 12x24 and 99 AM 2744 for the 101.27440 12x36 (the two early 12" with QCGB) and the QCGB itself, 99 A 02014 for 101.20140. That was in the 1951 catalogs. This was also the first time that they assigned unique catalog numbers to different bed lengths. Prior to that, for example, 101.07403 was the model number for the 12" Timken bearing lathe with power cross feed, regardless of whether it had a 36", 42", 48" or 54" bed.
