Mopar electronic ignition wiring schematic question

^^I doubt you have a 5 pin ECU. You cannot tell by looking. Many especially aftermarket (that is one) ECU have 5 PHYSICAL pins but the 5th is unconnected. Without ohms test to the rest of the pins you cannot tell. But that is a "newer looking aftermarket" and I'd bet it is a 4. Running a 4 pin ballast won't hurt, it simply doesn't use the other section

How to tell for sure? Easy. After you get it all wired up and running. Measure all 4 pins with the engine running. The two which are jumpered together will measure "same as battery" that is whatever the running V is (13.8--14.2) If the other two are both used, they will measure somewhat LESS than that showing that current is dropping voltage through them. If one is unused, it will be same as the supply pins