i failed smog a couple times and after alot of searching here and the web i found i had half DuraSpark II and Half a DuraSpark III ignition installed and had a High alt sensor added to the loop. i was not able to track down a mid rpm miss. After researh i found my vin showed a non-feedback carb and a computer under the dash. i decided to let the distribtor make the dession it was a vacuum advance DuraSpark II unit so i was going to drop the DuraSpark III, computer, High alt sensor and the O2 sensor. here was the DuraSpark III and sensor.
the DuraSpark III has 3 connectors and the DuraSpark II has II. the 3rd connection has 2 legs one to the high alt sensor and then to the computer and the other to the O2 sensor.
all the books i found on the EEC said it was located under the driver seat, but steve83 here said look above the gas pedal, steve was again right (as always)
the swap is very easy (if you do not have the feed back carb ((was found it will work fine but best swapped to non feedback unit) and a vacuum distributor..again i had all this in place. so it was unplug the 3 connections to the DuraSpark unit and undo the 3 10 MM bolts located in the drivers fender wheel well. pull the DuraSpark III (and high alt sensor in my case) and toss aside. reuse the 3 10 MM bolts on the DuraSpark II unit and connect the 2 connectors (one 2 wire and one 4 wire plug). i guess ther are a few DuraSpark II units look for the ones with a "Blue" strain relief (where the wires connect o the box). i got mine from the junkyard think i had the same unit already and wanted t see if that was my miss.
if you do not like junkyard parts a new DuraSpark sells for $23-30 at most auto places.
summary after install----i had a hotter spark and it moved the base timing to 28 degrees advance. i moved bake to 8 degress (smog test) and it run real good there was a huge seat of the pants feel change and now it idles smooth and starts right up in the am. there is not much on the web on DuraSpark III so i wanted to show what i did. i going to remove the dash computer (EEC) and toss it. I going to remove the O2 and install a air/fuel meter and that way i can watch and adjust as needed. if you choose to do this look at your wiring diagram and if it does not show the O2 or you are pre 84 I^ then you can use the DuraSpark II. my milage has picked up some too...i still need to swap the cat--i hoe this weekend..........mike