For several years, ARC has been making billet crankshafts with splined PTO shafts to provide the added strength some of today's larger, more powerful cars require, but the availability of posts for various clutch assemblies has been limited. So we decided to make our own.The main post is made of 7075 T6 Billet Aluminum. The replaceable collar is made of steel and is assembled to the post via piloted LEFT-HAND threads so the direction of resistence from the engine to the belt keeps the collar tight. Posts and collars will be available soon for ALL the major Torque-Converters used today.