halftracks

The M15 was equipped with the M42 armored weapon mount, with two water-cooled coaxial M2 Browning machine guns above a 37 mm gun. A total of 680 M15s were produced in 1943 by White and Autocar before the considerable stress this mount placed on the M3 chassis resulted in its replacement with the M54 mount. The new mount reversed weapon placement, used simpler and lighter air-cooled M2 Brownings, and added a M6 sighting system.
The resulting combination of the M54 mount with the M3A1 Halftrack chassis was designated the M15A1 CGMC. A total of 1,052 were produced in 1943, and a further 600 in 1944. 100 M15s were shipped to the Soviet Union under the Lend-Lease policy. Both the M42 mount and M15 CGMC were classified as obsolete in August 1946.
https://en.wikipedia.org/wiki/M15_Halftrack

M15A1 Halftrack in Normandy several days after the D-day landings