RIC lists 7 workshops for this issue, but gamma is not noted.
Valentinian I
A.D. 364-367
26x27mm 8.3gm
D N VALENTINI-ANVS P F AVG; pearl-diademed, draped and cuirassed bust right.
RESTITVTOR REIPVBLICAE; emperor standing facing, head right, holding labarum and Victory on globe.
In ex. SMNΓ
RIC IX Nicomedia 2a