The SM 4618 is a heavy-duty Starter Drive (Self Drive) engineered specifically for the Tata 407 New Model (including BS-III and BS-IV variants). While it retains the standard 9-tooth pinion, it features a specialized 10-spline internal bore to match the updated starter armature shafts found in newer Tata 407 LCVs. Utilizing a robust L-Type architecture, this unit is built to provide reliable cranking for the high-torque Tata 4SP CR4 and Turbo engines.