Clayton Mark 5451 Hydrant Head 2575K Complete Head. This Head Also Works For Models That Have 2506K, 2506-K, or 2506 On The Handle. The inner diameter of the threads that connect the head to the pipe measure approximately 1 1/4 inches. It is important when replacing the head that you loosen the packing and linkage before using pipe wrenches to unscrew the head. This is to prevent unscrewing the long rod from the plunger at the bottom of the hydrant. The clevis rod does come with the new head. The head comes just as pictured with the hose adaptor, draw straps for the handle, handle, packing nut, and pivot connector.