Spector,
As Tigerman says, the IS-2 beagan production in early '44. The IS-2m began to be seen later in the year, and had much improved hull armor, and a slightly different mantlet. If you compare pictures of the DML models, you can see the hull differences. Both tanks saw action in the war, there are rumors that some IS-3 saw action in the last days of the wa, but that hasn't been confirmed. If you want to go with a small scale, I also suggest you check out PST's models. Here's a link: http://www.internethobbies.com/internethobbies/pstmodels.html
I'm currently building one of their kits, a captured KV-1, and its pretty decent, although the track links are a PITA, and don't look very accurate. They may get some heavy weathering!
Tigerman: Thanks for the welcome!