From the post:
German ingenuity and efficiency have bought a new weapon to the Bolt Action battlefields – the new Pak 40 auf RSO… available in three different options. Crew with either Heer, Heer in Winter equipment, or Waffen-SS uniforms.
In 1943, some 60 Raupenschlepper Ost (RSOs), were modified by mounting a Pak 40 anti-tank gun and some light armour plates for the protection of the crew from small arms fire.
The resulting tank destroyer, regardless of the fact that it was quite slow due to the weight of these additions, was rushed into use to face the growing threat of the Soviet armoured divisions.