These RTS black polyurethane motor mounts for S/B and B/B Chev are much stronger than OE rubber mounts but still reduce vibration. Will also fit Holden HK HT HG with 253,308, SB & BB Chev Limits unwanted movement thereby putting more power to the wheels Tough like solid metal mounts without the vibration and noise Resistant to oil, chemicals and road contaminants that typically deteriorate rubber Specially deigned to be much stronger than OE rubber mounts Limits unwanted movement there by putting more power to the wheels They are tough like solid metal mounts without the vibration and noise resistant to oil, chemicals and road contaminants that typically deteriorate rubber Features a black polyurethane construction and designed to fit Small and Big Block Chev engines