In 1984 the first chassis was adapted to house the Hart 415T engine and become the "101B", with new sidepods. Later a new better build chassis was built and debuted at the 1984 San Marino Grand Prix, while the first was later newly modified as "101C" to adopt the Ford Cosworth DFV (third type of engine in few months), with the previous year side pods, and after the Detroit refitted with Hart engines to be used as T-Car.