Front Knuckle Arm Bolt OEM 240Z 260Z 280Z 510OEM Genuine Nissan knuckle arm bolt. There are two different bolt sizes that hold the knuckle arm on and this bolt is 40mm overall length (30mm under head length). This bolt will fit Datsun 240Z, 260Z, 280Z and 510 1970 78. The knuckle arm is located on the front suspernsion under the strut housing. Only 2mm difference in length between the long and short bolt.