|Date of first acceptance||July 1942||Total acceptances||80|
|T28E1: Dimensions||Gun overhang forward||0"||Front tread||64.5"
|37mm Gun M1A2||Behind cab||140 rounds||360°
|+80° to 0°
|Two .50cal M2 MG||Coaxial to 37mm gun||3,400 rounds
|+80° to 0°
|Sighting system M2E1|
|Rolled face-hardened steel|
|Location||Thickness||Angle from vertical|
|Engine||White 160AX; 6 cylinder, 4 cycle, in-line gasoline|
|Horsepower||Net: 147@3,000rpm||Torque||Net: 325 ft-lb@1,200rpm|
|Transmission||Spicer 3461 constant mesh, 4 speeds forward, 1 reverse|
|Type||Road wheels||Track return rollers|
|Front: Semi-elliptic longitudinal leaf spring
Rear: Vertical volute spring
|Front: Steel ventilated disc
Rear: 1 bogie/track;
|Drive sprockets||Idlers||Shock absorbers||18-tooth front drive||Spring-loaded at rear of track||On front wheels|
|Center guide band type|
|Pitches/track||58||Track ground contact length||46.75"
|Min turning diameter||59'
The T28E1 was based on the half-track personnel carrier M3. The rear armor was deleted, the fuel tanks were placed directly aft of the cab, and a gun mount for an automatic 37mm gun using the top portion of the 37mm gun carriage M3E1 and two water-cooled .50cal MGs was installed in the former passenger compartment. Elevation to the front could not be lower than +20° due to interference with the cab structure. Two thousand .50cal rounds were stowed around the gun mount in ten ammunition chests, with the remainder in a stowage compartment in the rear of the vehicle. Once in service, mechanics modified the elevation mechanism to prevent the 37mm ammunition clip from binding against the gun mount when it ejected with the mount at +15° or less; gun depression was also increased to -5°.