X3-37 is a synth courser working for the Institute in 2287.
Background
X3-37 is currently stationed somewhere in the Commonwealth, near either Poseidon Energy, Saugus Ironworks, or Abernathy farm.(Note) Justin Ayo orders Alana Secord to have them respond to a report of an escaped synth in that area.[1]
Note
^ (Note) Because the source of this information is a randomized conversation, it is not possible to specify which location.
Appearances
X3-37 is mentioned only in Fallout 4.