7.5cm PaK40/4 auf Raupenschlepper, Ost (Sf)
In August of 1943, the Waffenamt (Armaments Office) was approached by Steyr Werke with a proposal to mount the powerful 7.5cm PaK40 on the RSO tractor. The Waffenamt was favourably impressed with the idea and ordered the conversion of 50 vehicles.
The running gear of the RSO remained unchanged in the new vehicle. The driver's compartment is replaced with a low, lightly armoured superstructure. The weapon was mounted to the frame underneath the normal RSO bed. Army Group South received several of these vehicles for troop testing in early 1944.
Hitler was so impressed with the design he ordered a full-scale production plan for 1944. In March 60 were to be produced with a further 100 in April, 150 in May and 200 in June, with production ramped up to 400 per month from July 1944 onwards. The production plan was never put into effect, and only 60 vehicles were ever completed.
The result was a lightweight, mobile but highly exposed anti-tank weapon. The RSO/PaK40 combination was manufactured during 1943/44 and was primarily used to support anti-tank infantry units on the Eastern Front.
The PaK40 auf RSO tank-hunters were put on field trials with Army Group South. Of the 60 RSO/4 with PAK 40 14 each were given to Heer Panzerjägerabteilungen 743 and 744, 14 were issued to 18. Panzergrenadierdivision and 7 were given to 1. Ski-Jäger Brigade. They were not considered satisfactory on account of their low speed and noisy engine.
