This is a later-production M10, evidenced by the lack of auxiliary armor bosses on the turret and hull sides. Under the sloping hull armor, the M4A2 Sherman origins of the M10 can be made out by focusing on the running gear and lower hull front. The gun shield on the M10 is triangular, compared to the more rounded one on the 90mm GMC M36. This vehicle is sitting on T48 rubber track.
This rear view of shows tool stowage on the rear plate as well as the shape of the exhaust baffle. The gun is in its rest on the rear of the top deck, and the tow pintle can be seen below the two engine exhaust pipes. (Picture from TM 9-752 3-inch Gun Motor Carriage M10.)
The internal arrangement of the vehicle can be seen in this cross-sectional view. (Picture from TM 9-752 3-inch Gun Motor Carriage M10.)
This overhead view allows us to see the partial roof provided to the turret crew. This very early machine has stowage for track grousers on the turret rear instead of the counterweights. The grousers were moved to racks on the hull side after their displacement from the turret. (Picture from TM 9-752 3-inch Gun Motor Carriage M10.)
The attachment of the counterweights on the turret rear is highlighted here.
Each counterweight added 1800lb (820kg) to the back of the turret, easing the manual traverse effort on uneven ground.
The duckbill-style counterweights can be seen on this machine. (Picture from Tank Data, volume 3.)
Fixtures on the rear deck of the M10 are labeled in this illustration. (Picture from TM 9-1750L Hull and Turret Electrical Systems, Tracks and Suspension for 3-inch Gun Motor Carriages M10 and M10A1.)
A later version of the engine deck is shown here; note the extra armored cap between the engine grilles and the gun rest bracket in the foreground. Later in production, improvements to the engine lubrication system were introduced that reduced particulate levels and increased cooling. The new cover protected an engine oil gauge added at the same time. The red fire extinguisher controls can be see surrounded by a housing to the upper left of the image.
This is an earlier-production vehicle, as it retains the auxiliary armor bosses on the hull and turret sides. Both T48 and T51 track blocks are stowed on the vehicle's final drive and differential cover.
The underside of the driver's hatch is highlighted here. The periscope mount is obvious, but the periscope itself is missing.
The driver's position is shown here from outside of his hatch. His instrument panel is visible to the left, steering levers are present in front of his seat, and the white gear shift lever is between the seat and the transmission itself to the right.
The drivers' compartment is illustrated in this image. (Picture from TM 9-752 3-inch Gun Motor Carriage M10.)
The driver's controls are labeled here. A. Steering levers. B. Clutch lockouts. C. Throttle locking lever. D. Throttle. E. Gearshift lever. F. Brake locking pedal. G. Accelerator pedal. H. Clutch pedal. (Picture from TM 9-752 3-inch Gun Motor Carriage M10.)
Details of the gun's breech assembly are shown in this picture. (Picture from TM 9-752 3-inch Gun Motor Carriage M10.)
The opposite side of the breech assembly is shown here. An elevation handwheel was available on each side of the weapon. (Picture from TM 9-752 3-inch Gun Motor Carriage M10.)
The turret of this vehicle is traversed to the right, and this view is looking through the turret into the hull. The fighting compartment floor is green, while the white hull floor and assistant driver's seat can be seen to the left. The propellor shaft is visible just to the left of the hull floor escape hatch. The handwheel to the left of the image is for turret traverse, and the other is for gun elevation.
The turret crew was provided with folding seats affixed to the turret ring. This seat on the turret's right side belonged to the vehicle commander. The gunner and loader sat on the turret's left side. Stowage for 3" ammunition can be seen in the hull.
Rear turret stowage of 3" ammunition and a submachine gun is illustrated here. Six 3" rounds, one of which is obscured by the Thompson, were stowed in this area. (Picture from TM 9-752 3-inch Gun Motor Carriage M10.)
The twin diesel engines are shown outside of the engine compartment in this picture. (Picture from TM 9-752 3-inch Gun Motor Carriage M10.)
The rear of the vehicle is to the left of this image. The twin GM 6-71 engines that make up the 6046 are visible here. Red paint is fading from the now silver valve rocker covers. The water outlet manifolds are just inboard of the rocker covers, and the exhaust manifolds are in the middle. The black cylindrical air cleaners can be seen to the top of the image. The knobs to the left are for the drain valve and handle assembly.
The engine air cleaners can be better seen in this picture. The cylinder to the right of the forward air cleaner is a secondary fuel filter.
The rear of the engine compartment is shown here. The engine fans are behind their protective mesh shrouds, and the thermostat housings and water outlet tubes are visible in the center of the image. The engine oil gauge added during production can also be seen.
Details of ammunition stowage are diagrammed here. Typically, the 3" ammunition mix was 75% armor-piercing and 25% high explosive. (Picture from TM 9-752 3-inch Gun Motor Carriage M10.)
This earlier-production vehicle also has auxiliary armor bosses on the turret and hull sides. There is an indentation for an antenna mount in the hull side. The .50cal machine gun is mounted, and stowage for a towing cable is visible. (Picture from TM 9-1750L Hull and Turret Electrical Systems, Tracks and Suspension for 3-inch Gun Motor Carriages M10 and M10A1.)
The different exhaust baffle for the GAA engine serves to identify this machine as an M10A1. (Picture from TM 9-731G 3-inch Gun Motor Carriage M10A1.)
Compared to the rear deck on the M10, that of the M10A1 featured wider air intake grille doors. The different arrangement of the various filler caps and the fire extinguisher handles can also be seen. (Picture from TM 9-731G 3-inch Gun Motor Carriage M10A1.)
The driver's station is shown in this picture. Since the M10A1 had a single engine, the clutch lockouts found on the M10 were absent. (Picture from TM 9-731G 3-inch Gun Motor Carriage M10A1.)