An interesting cold war design grows up.
The T92 Light Tank was an innovative American light tank developed in 1950s by Aircraft Armaments. At 18.5 tonnes, 5m length, it was designed as an airborne/airdropped replacement for the 5 tonnes heavier M41 Walker Bulldog. The T92 was never accepted into service.
The main gun was a conventional 76 mm cannon with a very low profile turret. Little more was exposed than the main gun and two crew cupolas which allowed 50 caliber and 30 caliber machine guns to fire buttoned up. The engine was moved to the front, which increased protection, and a rear access door provided an escape hatch and protection while reloading; this layout was later adopted by the contemporary Israeli Merkava battle tank. It had a crew of four with a semi-automatic loading system. It carried 60 main gun rounds, and automatically ejected spent shell casings.