Thread is 10x1.25... on the late model motors, not sure if you can find an ARP bolt in that size. I would run NEW factory bolts, loctite and also look at getting the thing dowelled if you have any more concerns, there is play in the bolts and the flywheel iis actually clamped on the head of the bolt not on the shank of the bolt, 3 4mm dowels 120° apart should do the job, the end of the crank is soft unlike the journals and easy to drill.