The first of the Dennis RS fire appliances were fitted with Perkins V8 diesel engines, either the V8-540 (8.8 litre) or the V8-640 (10.6 litre), with or without turbochargers. The all-welded steel cab provided the maximum protection possible to the crew, and had an edge over other commercial trucks, as the RS was a purpose built fire appliance and was not used for any other application. The Dennis RS could be fitted with a variety of bodies by Dennis/JDC, Carmichael, Fulton Wylie, etc.