Rare T-70

Here's a pretty standard photo of some tanks being shipped by railroad.

But wait, what is this? Zoom, enhance!

It's a T-70. But no ordinary T-70! It's a very rare T-70 with a cast turret. Only three such turrets were made. The turret was discovered to be inferior to the welded one, and no one had the resources to develop (or even produce) a better version. 

The tank was originally to be manufactured with a cast turret designed by Dedkov, but it was replaced with a welded one before the tank entered production.