Disconnect wires and loosen/remove clamp at base, pull up and out. Put new/diff 1 in. Take cap off before you remove and mark where rotor is pointing using reference on engine. As you remove, the rotor will turn a little. When you you put new in you have to allow for this slight spin. So that when seated, the mark you referenced lines up. Dont forget to replace 'O' ring or gasket on mounting base of distributor.