Comparing: S35 CA vs. SU-85 vs. SU-85I

The design called for the conversion of tanks into tank destroyers by mounting a 17-pounder gun into an open-topped, lightly armored cabin.

Developed on the basis of the T-34 medium tank and the SU-122 assault gun. Produced from August 1943 through July 1944. The 85-mm D-5S gun allowed the SU-85 to effectively hit enemy medium tanks at distances of more than 1,000 meters and to penetrate the front armor of heavy tanks at shorter distances.

A proposed modification of captured German Pz.Kpfw. III tanks, which were to be mounted with the 85 mm gun. Never entered mass production nor saw service.