The McCormick 6678334A1 Pulley is a genuine OEM replacement part designed for various McCormick X-series tractors. This essential component ensures proper belt tension and smooth operation within the engine system, contributing to reliable performance and longevity. It is compatible with models including X4.20, X4.30, X4.40, X4.50, X4.60, X4.70, X4.35, X4.45, X4.55, X4.65, X5.35, X5.45, X5.55, X5.65, X5.75, X5.85, X6.420, X6.430, X6.440, X6.460, X6.470, X6.480, X6.490, X7.440, X7.460, X7.470, X7.480, X7.650, X7.660, X7.670, X7.680, X8.660, X8.670, X8.680, X8.690.