Porsche ARP 204 5001 M96 M97 Carrier Through Bolt Kit Porsche Boxster Cayman 911 204 5001 SMC23011 Years 1956 1959 964.106.036.20 Years 1956 1959 Porsche The Flat 6 Innovations Billet Aluminum Hard Anodized M96 M97 Underdrive Crankshaft Pulley manufactured by LN Engineering offers increased horsepower and torque by reducing parasitic losses by slowing down the belt driven accessories Porsche Porsche 986 987 996 997 Crankshaft Carrier Through Bolt Kit This ARP crankshaft carrier thru bolt kit features bolts that are stronger (and reusable) to help prevent shuffling and fretting of the main bearing saddles common to engines that see high performance driving or have been increased in displacement