Distributor seal broke, water in 2 cylinders

Which seal are you referring to?

For the horn, do you hear the relay click when you press the button?

Yup. A picture would be helpful. There's only one fuel supply line and one return line to the tank. I think you might be referring to the 8 spark plug wires.

If the click is coming from under the dash when you press the horn button, that would be the relay clicking. That means the horn fuse is good. This photo is from Rockauto. Com and shows what the horns could look like. There are usually two of them, a high note and a low note. They are usually mounted next to each other, typically to the side of the radiator, but they might be on the inner fender too.

Most of the time one horn shorts and causes the fuse to blow. Then the relay won't click either when you press the horn button. It's rare for both horns to stop working at the same time and the fuse is still good. That would imply the wire going to the horns has a break in it. To check for that, you'll need a test light or digital voltmeter to test for voltage on that horn wire. The ground wire could be corroded off too.

Caradiodoc

Dandy. That doesn't have anything to do with age. Water will affect any distributor. Chrysler has a lot less trouble with water because the distributor sits way in the back of the engine. The clue is there will still be spark from the ignition coil. To test for that spark, unplug the coil wire from the center terminal in the distributor cap, then wedge that end so the brass terminal is about 1/4" away from any metal part on the engine. Have a helper crank the engine for a few seconds while you watch for nice strong sparks from that wire.

Caradiodoc

So what you're saying is you shouldn't be driving a truck. You should be driving a submarine! Sorry; I couldn't help myself.

Based on the water problem, ... By the way, how do you know two cylinders aren't firing. Is it just due to how it feels or did you do some testing to identify the specific dead cylinders?

Based on the history, I would suspect carbon-tracking on the distributor cap. Condensation can form inside the cap. The spark voltage looks for the easiest way to ground and that water conducts a whole lot better than a spark plug and wire. Once the spark is shorted out that way, it leaves a carbon track behind. Carbon is also a pretty good conductor. That can happen on the outside of the cap too but you'll be able to see that. If you catch that soon enough you can clean off the carbon but usually it burns into the cap so it has to be replaced.

If the horn relay isn't clicking, there is likely a blown fuse and shorted horn. There could also be a bad ground strap on the steering column. Do you have an air bag in the steering wheel? One quick thing you can try is to remove the cover from the horn relay, reinstall it without the cover, then squeeze the contact to see if the horn blows. That will determine which part of the circuit has the problem.

Caradiodoc

Yup, you don't know what you're talking about. :) If you mean the headlight wires are in the same wiring harness, that is full of wires for all kinds of different circuits. A short on the horn circuit is not part of the head light circuit just because their wires are bundled together.

What you might want to try is unplugging the wire from the horn, then use a test light or a voltmeter to see if voltage appears there when you press the horn button. I can walk you through the steps if necessary. If you have voltage there, you might want to visit a salvage yard for a good used horn. There are yards in larger cities where you pay your buck and grab one of their wheel barrows to haul your tool box around, then you can spend all day harvesting parts.