I'm fixing a a 1976 Fireball Home Edition and the right slingshot coil (AP-23-750) needs replaced. The one I ordered does not have a diode and I'm unsure of what to get, it's hard to tell from the old diode which one it is. I know there is a 40 and a 70 on the diode and it is blue. Which diode should go on the coil?