I believe I have M12x1.25x50. The bolts are 10.9 grade. But after comparing the old boltSort of curious where you got the bolts for the new setup. Those bolts are a special thread and extremely high grade. On the Cummins 4bt damper the only source I ever found for those was Cummins. Yours may actually be about the same length as those since you had that adapter on the front. Those 3924584 bolts are M12x1.25x60 mm flange head grade 12.9 or higher. Also probably one of the 2 places on the engine where red Loctite is recommended. The other is the flywheel bolts.