This is 1 x 1952 - 1955 Cadillac cylinder head 3 1/2” bolt. The measurements are as follows: 7/16”-14 x 3 1/2” the bolt overall length is 3.837 / bolt length is 3.508. Thread length is .771 / diameter .388. These will fit all models of 1952 - 1955. These are good used original bolts, the threads are all good, there is nothing wrong with these. Sold As Is, As Shown.