Unfortunately, every time I click on one of your images it always loads up the first picture you posted so I can't see any of the other images in large enough size to make out any details.
From the thumbnails it looks as though it might be an electrical or electronics part. If that's correct then it could be part of the radio system, the sighting system, the turret power system and so on.
If you can positively identify what it is, you can probably find someone who will want to buy it but I have no idea how much it could sell for.