Thru-Bolt - 1/4-20 x 7-1/2" Hex Washer Head; 3/8" Drive - Delco 20MT,25MT,27MT Starters (3300, 3601, 3725, 4000, 4038, 4193, 4266, 4267, 4271, 4272, 4274, 4275, 4276, 4280, 4283, 4307, 4318, 4392, 4393, 4398, 4516, 4537, 4677, 4778, 4949, 6147, 6157, 6162, 6164, 6165, 6166, 6167, 6168, 6173, 6177, 6179, 6180, 6305, 6512, 6519, 6521, 6542, 6543, 6735, 6736, 6737, 6738, 6739, 6743)