The classification "44" stands for the T-44 tank chassis, which the tank was designed after. The tank started its life on the drawing board in early 1944. It had a 122 mm (4.8 in) D-25-44S gun, with its firing and ammunition compartment up front. It had a greatly sloped 90 mm (3.5 in) front armor plate, with an inclination of 27 degrees. The side plates were 75 mm (3.0 in) thick, and the back plates were 45 mm (1.8 in). The design though was found to be too heavy and too large, while the SU-100-M-2 wasn't, and on March 7th 1945 all work on the tank was terminated.
You can download this paper model template here: World of Tanks - SU-122-44 Self-Propelled Artillery Free Paper Model Download