Yes its a BCS, good eye! And you are right about it being old. Its about twice my age. Wery popular here still. Every house has one. In the past times this was a work horse of the farmer. It powered all sort of things. The slow turning 500ccm engine has “woodgas” written all over it but unfortunaly a conversion wuld be hard. Those things work on extremely steep terrain, often so steep only one wheel touches the ground.