My Grandfather fought in WWII for the Soviets. He divulged limited information before he died and never did talk about the war. Just prior to the war he was in a Calvary unit but during the war he was an ambulance driver, and he served on the Iranian front. He never told us his rank, or really what much he did. I was wondering where I could go or how I could obtain information regarding his service.
So I'm assuming you can read Russian? If so, there should be a national archives for the Soviet Union still in existence. I have absolutely no idea how to read Russian or access that material, but they usually have an absolute wealth of background information for the Soviet armed forces. Though it could be that his files were destroyed depending on where/when he enrolled. Do you know the answer to that?