How about possibly introducing some heavy assault tanks like the Brummbar assault gun for the Axis forces, and the Su-152 for the Allies forces?
Sorry to take pictures from another game, but seems the best colored detailed picture of these tanks;
Brummbar: http://forgottenhope.bf1942files.com/images/vehicles/Sturmpanzer IV Brummbaer/big.jpg
And the Su-152: http://forgottenhope.bf1942files.com/images/news/161 - SU152.jpg
Sorry to take pictures from another game, but seems the best colored detailed picture of these tanks;
Brummbar: http://forgottenhope.bf1942files.com/images/vehicles/Sturmpanzer IV Brummbaer/big.jpg
And the Su-152: http://forgottenhope.bf1942files.com/images/news/161 - SU152.jpg