I ordered a new ECU and ballast on Friday that came in today. The ECU was part #LX-101 - 4 pin electronic control unit. I actually wanted the 5 pin ECU and found the part number on another post. It is part #LX-100.
Just reordered the right one.

The ballast that came in was also the 2 pin part #RU-4. I wanted the 4 pin ballast. WHAT PART NUMBER IS THE 4 PIN BALLAST FROM STANDARD?

Why do you want the 5-pin module?

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Joshua

The car came with a 5 pin. I want to keep it as original as possible. I really hate that the ECU will not say MOPAR as the original did in '74 when I bought it. SSD says Mopar ECUs are Chinese junk. Fine, I'll go with Standard.

I have heard that one of those pins (red w/ green tracer) doesn't do anything. If that's the case, why did they have a 5 pin ECU and why do they still make 5 pin replacement ECUs?

Still need 4 pin ballast resistor Standard part number.

The 5th wire was used with the 5 ohm resistor in the ballast resistor. I've been told, but have not verified that the external resistor was used to bias the power transistor. In any case the functionality of that resistor and wire was moved inside the 4-pin module. Most manufacturers do not make the obsolete 5-pin module as it is replaced directly by the 4-pin module.

Go to rockauto.com if you want the part number for your ballast resistor.

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Joshua