German tanks, as stated, were buff (ivory) inside with a neutral gray below the sponsons. US tanks were white inside with white interior lights (can't remember if there as a red lens also, but I'm pretty sure there wasn't). One light was over the main gun on most tanks, another between the driver and bow gunner and yet another (on M5A1's) over the bow machine gun for loading. Instrument panels and sights were lit also for ops at night. British tanks were silver inside, if the Churchill and Cenurion at the Patton Museum are correct!
The US interior lights were round with the lens being a bit smaller than the body (about 4 inches in diameter total for the assembly).
Hope this helps.
Ron.