Distributor retrofit kit.

Retrofit to What? That truck already came with a distributor. If they updated it, that's all that would be available now anyway.

You can't just disconnect the electronics. The system is engineered that way and will be looking for those signals to operate.

I'm not aware of any kit and there are no TSBs referring to it.

No, you cannot just disconnect the electronics

No, you CAN'T just do anything to it. It has a computer and the advance system is tied into it.

Both guys are right, but what exactly is the symptom? You should have the 5-pin ignition module as shown in this photo from rockauto. Com. That IS what was included in the retrofit kit along with the distributor you already have with the vacuum and mechanical advance built in. That retrofit kit was designed for people who wanted to upgrade their breaker point systems to what you have now. Your system was first used on Dodges in 1972 and on Chryslers and Plymouths in 1973. That was the industry's first product line-wide use of electronic ignition without breaker points. It was extremely reliable and easy to diagnose. Probably their best ignition system ever in terms of reliability. Your distributor will have the vacuum advance unit hanging on the side. If the timing is bouncing around causing erratic idle speed, the first suspect is worn bushings around the distributor shaft. If you put in a used distributor and had the same problem, it too could have a worn bushing, although that wasn't real common. Another possibility is a sloppy timing chain.

If your van uses a version of the "Lean Burn" system, you'll have an Engine Computer hanging off the air cleaner housing or on the firewall under the middle of the windshield. That does the vacuum and mechanical advance rather than the distributor. There won't be any vacuum advance unit on the distributor. It will be on the computer. Back in the day when when I was young(er) and stupid(er), I observed that there was no timing advance taking place on my 318. I knew it was done by the computer but I didn't know how to test it, so I just dropped in an older distributor with the vacuum advance built in. The camshaft gear and the electrical connector are the same, and it uses the same distributor cap and rotor.

There were some models that used two pickup coils. One was switched in during cranking to retard timing so it would crank easier, then the relay would switch to the other pickup coil for running. If you have a distributor now with two pickup coils, you'll need the older style with two coils or you must bypass that relay. Otherwise it will only run during cranking or during running after you release the ignition switch, depending on which of the two connectors you use. Check the vacuum hose for leaks. On mine, I left that port open when I put the older distributor in, and it ran fine for about 50,000 miles, then it developed a surging on the highway. Capping that unused port solved the surging. I was still running on the Lean Burn Computer even though it wasn't involved with timing advance any longer. Now that I'm a little smarter, check the operation of your other sensors to see why your timing isn't advancing, (if that's the problem you're having). The electronic timing advance is cancelled when the throttle position sensor is at idle, and when the coolant temperature sensor is disconnected. That's how it was put into base timing mode to set the distributor. The vacuum transducer on the computer could be defective too. I don't think it is a separately replaceable part. You would need to replace the entire computer.

I also see a reference to a crankshaft position sensor but I don't recall those being used as far back as an '85 model. If you have that bolted behind the passenger side cylinder head, all timing advance is done by the computer. The camshaft sensor is built into the distributor and synchronizes injector timing. There's nothing you can do to alter the ignition timing on those systems. THAT'S where trying to go backwards to that retrofit kit would get real involved and impractical. You'd still need the computer to run the injectors, and it needs the pulses from both sensors. It's going to try to advance the timing and so would the older distributor. You'd have an electrical and running mess. If you still have a carburetor, you don't have this computer system.

The reason they don't make that retrofit kit any longer is all those parts are readily available in the salvage yards and auto parts stores. I adapted my car to the five-pin ignition module from the Lean Burn computer, with scrap parts almost 30 years ago, but both systems used a carburetor. Neither was ever used with fuel injection. It was a simple matter of unplugging the Lean Burn Computer and tapping into a couple of wires to run to the new box. It sounds like that's what you're trying to do, but you would be retrofitting from what you probably have now to the same thing.

The Electronic Spark Advance provides electronically controlled spark advance and eliminates the need for mechanical and vacuum advance controls in the distributor. The Spark Control Computer uses as many as six sensors to monitor the engines conditions so that it can fire the spark plugs at the proper time.

SPARK CONTROL COMPUTER (SCC)
The Spark Control Computer is the heart of the entire system. It gives the capability of igniting the fuel mixture according to different modes of engine operation by delivering an infinite amount of variable advance curves. During cranking, an electrical signal from the distributor is fed into the computer. This signal will cause the computer to fire the spark plugs at a fixed amount of advance. Once the engine starts, the timing will now be controlled by the computer based on the information received from the various sensors.
The amount of spark advance is determined by three factors, coolant temperature, engine speed, and manifold vacuum. The computer determines spark advance in the following manner:

1. Coolant temperature modifies vacuum advance schedule. There is a different schedule for hot and for cold engines.
2. Advance from vacuum is programmed into computer. In a cold or warm engine spark advance depends only on amount of manifold vacuum. In a hot engine spark advance depends on both manifold vacuum and engine speed.
3. Advance from speed is programmed into computer and depends only engine speed.

SENSORS
The Electronic Spark Control System incorporates the following sensors:

1. The Hall Effect Pickup assembly, located in distributor, supplies basic timing signal and engine speed to computer.
2. The coolant sensor, located on thermostat housing, gives computer information on engine temperature.
3. A carburetor switch located on end of idle stop tells computer when engine is at an idle.
4. The vacuum transducer is located on the Spark Control Computer and tells computer how much vacuum engine is producing.
5. The oxygen sensor (used with Feed Back carburetor only) is located in exhaust manifold and informs computer about oxygen in exhaust so it can alter air/fuel mixture.
6. A charge temperature switch (on 6 cyl. Engines only) is located on intake manifold and monitors intake air temperature.