The hull remained riveted, but the driver and gunner received
new hatches with new protectoscope vision slot covers.
At later production stages,
grouser boxes were added to both rear sides, as well as
additional fuel tanks on both rear sponsons, thus doubling the tank's range, as shown with the
M3A1.
Special thanks to Mr. Claude Gillono, France, and Mr. Eduard Golovashkin, Russia, for providing precious informations.