131405,
is on the “front or operator’s side”
6158 is stamped into the “rear or back side” of the lathe.

It has a taper attachment, of note is the compound is “large dial” and the crossfeed is “small dial”.  Perhaps the compound was changed out during its life?
It’s the smaller threaded spindle bore.
It has several tags indicating it was used in the Navy at some point.
- one brass tag is simply stamped “50-12”
- another tag states that it “conforms to the war production board”
- another tag has three lines - 
1st line reads “navy yard number 55-149”
2nd line reads “MFG’s serial number 131405”
3rd line reads “Purchased 44” and then “COST$ 1320.24”
- another tag has 5 lines
1st line reads “245”
2nd line reads “U.S. NAVAL STATION”
3rd line reads “SAN DIEGO 36, CALIFORNIA”
4th line reads “U.S.  NAVY PROPERTY”
5th line reads “NAVY IDENTIFICATION NUMBER 0049”
-another tag just has 2 rows of digits, but it’s heavily painted and hard to read. 
1st line reads “PA00245l
2nd line reads “004918”
- another tag indicates that it was rebuilt at a place called FROST Rebuilding Company.  Complete machine tool service.  Precision scraping, hydraulics, machine design.  Los Angeles, Calif.  I believe the date reads 8-89, but it’s poorly stamped.

The machine does show indications of having had little use, or freshly scraped.  Bed, saddle, cross-slide making surface all show recent scraping / frosting marks.