No spark I Install new distributor?

79 could have a 302, 351, 400 or 460. There are 2 possible firing orders depending on which engine you have if it's the original engine. Set it on TDC cylinder one on the compression stroke. Then pull the cap off and look at where it's pointing. If it's at a terminal post, make that #1 and wire around counter clockwise following the correct order. Put a spark tester on the coil wire and see if it has spark out of the coil. If you have spark out of the coil and it's wired correctly then you should be able to put a timing light on the cylinder one wire and set the base timing.

I Put a spark tester on the coil wire to see if it has spark out of the coil. there was no spark out of the coil. what is the number for the timing? how do I know what engine is in the pickup truck?

OK, no spark from the coil can mean coil or the trigger is bad or more common the ESC box is bad. To test the coil is simple. Take a piece of wire, connect it to a good ground, connect the spark tester to the coil wire, turn on the key, now tap the grounded wire on the negative coil post, do you get a nice hot spark Yes= Coils Good, No= replace the coil. See if you have spark. Still no spark = find the box shown, Find the part number on it, get a replacement. As for engine size, if it's stock there should be a sticker on the radiator support that tells you the engine size, timing and spark plug gap.

what type of spark tester do I need to do this test?

Just a simple gap style tester, you could even use a plug wire and a plug. You are just testing if the coil fires on it's own.

I took a piece of wire, connect it to the negative side of the coil and I disconnect wire from the distributor cap and connect a spark plug into it and turn the key on and tough the piece of wire to a ground, the spark plug didn't spark unless I wiggle the key but as soon as I stop wiggling the key the spark plug stop sparkling, will that be something wrong with the Ignition switch? I also connect my test light to the positive side of the coil and turn on the key the test light come on bright, but when I connect the test light to the negative side of the coil my test light is dim, but when I wiggle the key the test light brightness up so what is going on here?

That sounds like the coil is OK but the ignition switch has a problem. How long has this truck sat around? It could be corrosion that some contact cleaner would help with, however being a 79 it may just need a new switch.

the truck was cranking and starting about a year ago with the key but it stop cranking with the key then I use a Jump wire to crank it from the starter switch to the battery, the engine and transmission was taken out for a rebuilding Job so aften it was put back in that when the engine stop starting.how can I do a bench test on the Ignition starter switch?

You pretty much already tested it. If it stopped cranking with the key then it likely isn't turning on the power to the ignition either. They are all related. The switch controls power to all the other areas and if it's not spinning the starter and now the power to the coil is out unless you jiggle the key, that sounds like a bad switch.

I replaced a new switch and it still doing the same thing. the coil is getting hot do it suppose to get hot?

Exactly what is it doing that is the same? No crank and no spark? You replaced the electronic switch behind the dash correct? If so you still have either corrosion or damage to hunt down. The service info I have doesn't have the wiring diagram for that vintage but I did find https://www.fordification.net/tech/wiring.htm and they show it as images at the bottom of the page. If you go there and download those so you have a reference we can do some testing.

when I turn the key to crank the truck nothing happen but I can take a piece off wire and touch one end to positive post on battery and the other end to the starter switch and the engine will crank but no spark from the wire running from coil or distributor cap and the coil get hot if the ignition switch stay on for a little while.

OK go grab those images and I'll look at them to see where things go, have to dust a few cobwebs out of the mind as the only vehicles that age around here are collectors and might be in a shop once a year. But I'm sure we will figure it out.

how do I test the coil with a multimeter? to see is it bad?

You test resistance from the + to - (primary winding) and then from the coil tap to each terminal (secondary winding). So first set your meter to the lowest ohms setting, now short the leads and write down the number that shows up (if your meter has a zeroing feature, set it to zero. Now put the meters plus lead on the coils plus terminal and the negative on the negative. You should see between 1point 3 and 1 point 8 ohms. Open circuit or higher than 3 ohms and it's likely junk. Now switch the meter to 20K ohms. Then test between the positive post and the coil post. There you should see between 8,000 and 12,000 on a good coil. Then check between the negative post and the coil tap and it should be the same reading within an ohm or two.

So a good coil might be 1.6 Primary and 9,480 ohms Secondary.
If you look on the coil you have and look up the part number it will tell you what the specs are but the numbers I gave are common numbers for a good coil.

(I set the multimeter to 2K I put the meters plus lead on the coils plus terminal and the negative on the negative. I see .002 ohms. Now I switch the meter to 20K ohms. Then test between the positive post and the coil post. I see 8.25 Then I check between the negative post and the coil and it is the same reading within an ohm.

Does your meter go lower than 2K The low reading is basically one point three ohms to one point nine ohms. .002 could be fine because the meter rounded up. What would be ideal is 100 ohms if it has it or try diode test if it has that.

My meter don't go lower than 2K.how do I test the Ignition control module?

There isn't much to test, does it have power and a good ground. Beyond that they either work or don't.
This video covers a lot of the issues with the duraspark system. There are multiple others as well. https://www.youtube.com/watch?v=RylhE4_HSPU Might be easier than following written words, especially coupled with the wiring diagrams.
Also you mentioned that turning the key does nothing, do you have power to the gauges and radio when you turn it to on? Then it does nothing when you turn it to start correct? Or do you get nothing? You said it was running ok a year ago but now doesn't so something changed. The common things are corrosion from setting, go over the battery cables and every plug and connection you can find and clean them especially grounds. Then go to the coil, do you have 6 or12 volts at the coil with the key on? How about when in start? If not then the problem isn't in the ignition system but in the wiring of the truck. What items work in the vehicle? Wipers? Lights? Radio? Gauges? Go to the fuse box with a simple test light and check all of the fuses with the light with the key off then on.

I havn't notice power to the gauges and radio when turn key on I did notice a red light come on. It does nothing when turn key to start. at once or twice I did loose power at the coil with the key on but I havn't tried it when in start position. I havn't tried to see will the wipers, radio, work yet but I notice the headlights work. I havn't check the fuses yet, does 12 volts suppose to be at the (+) and (-) side of the coil? how does the Ignition system work on this truck to get spark?

Battery power goes to the + side of the coil. The - side is the trigger. The ignition box has a three wire plug that goes to the inductive pick-up in the distributor. That is the trigger that tells the box when to fire. Then there is the second plug that carries power and a timing signal. It is a 3 part system. The box, distributer and coil work together. Test for power at the positive post on the coil, Then at the 2 wire plug to the ignitor box. (should be a Red wire with black stripe, but there were a few colors used, just like the ignition boxes. If you have power to those with the key on, then the key switch is working. However with the vehicle doing nothing when you turn the key, ignition isn't the problem, the power isn't getting through so we need to figure that out first, If you just want to see if the engine will run and jumping the solenoid gets it to turn over you could try an old trick. Take a length of wire, connect it to the power feed on the ignition box, then another to the positive terminal on the coil. Now jump the solenoid and see if it starts up. You cannot drive it this way because the constant 12 volts could burn out the coil and nothing else is going to work, but it should let you test the engine. To shut it off disconnect the wire to the battery.

12 volts at the positive and negative post on coil and the red wire with black stripe st the 2 wire plug to the Ignitor box with the on. so I run a wire from the red wire on the Ignitor box to the positive terminal on the coil and jump the solenoid but the engine didn't start. do I suppose to connect two wires from the power feed on on the Ignition box and positive terminal on the coil? I'm a little confused here. what color is the wire I suppose to connect to at the Ignition box?

There should not be 12 volts on the negative side, that points to something wired wrong or the ground side of the battery isn't connected very well. I would start there, Not having a good ground path may be causing all of these issues and can do a lot of damage to other parts. So start at the battery, remove the cables clean them. re-connect, repeat at each point they connect. Check the engine to chassis ground and the battery to frame and chassis grounds. Here is another simple test called a voltage drop test. Take your meter and set it to 20 volts or so. Now turn on something that draws power, headlights brake lights or similar. Now take the probes and connect one to battery positive, then to the battery connection on the fuse box, you should see close to zero volts. Now check the negative side by touching the battery negative post with one lead and the engine block with the other, Same thing here, you should see close to zero. Same from battery negative to any ground point on the truck. It's a fast way to see if there is a bad cable or connection, I have done this test on a no start vehicle and discovered that all of the current from the battery was being stopped at the point where the battery cable bolted to the clamp on the battery post. Because you have basically lost all power for starting and ignition you might find the bad connection this way.

What the volts should be on the negative side of the coil when turn key on? the negative side of the coil is it the trigger side from the Ignition control module? can I check for a signal at the coil or the ignition control module? the ground strap is not hooked up. do it connect from the engine to the fire wall. sometime when cranking I can see spark of fire at the starter solenoid.

The negative side is the trigger on the coil. The ignition works by grounding that side and then opening it, when it opens the magnetic field collapses and you get a spark. No way to check for the signal without an oscilloscope. The missing ground strap is part of the problem. You should have one negative cable from the negative side of the battery going to the engine block, then a second cable from the engine block to the firewall. Then another that goes from the negative to the body. And usually underneath there will be a cable connecting the cab to the box and another from the frame to the body. The ignition module for example has to be mounted and secured to have a ground, if you just plug it it without a good ground it will burn it out because of the lack of grounding.
The "spark" at the solenoid also indicates a poor connection. From the descriptions so far I would start there, don't even bother with the ignition or starter until you go through the connections and ensure they are all clean and tight, Then do the voltage drop test, it is possible to have a cable that looks find but actually is damaged internally.

I replaced the ESC box so now I have spark the truck tried to start but it is back firing I don't think the engine is time right I don't think i install the distributor correct. how do I install the distributor the correct way?

Backfiring can be timing or incorrect plug wire sequence. To install it correctly, pull all the spark plugs (makes rotating and setting it at TDC much easier. Now pull the distributor cap off, Rotate the engine until you get to top dead center on cylinder one. An easy way to tell is to put a finger or similar in the plug opening and listen and feel for the air pressure to increase as it comes up on compression. Now look on the damper and you should see a mark, line that up with the TDC point on the timing tab. Next set the distributor so the rotor lines up with the number one post on the cap. Then try to set it into place. Note how far the rotor moved, remove it and rotate the rotor back the same amount to the opposite side of the #1 plug wire post, now set it back in and if done correctly the rotor will turn and once seated it will all line up at TDC, Then clamp it in place. Now start it up and do the baseline timing using a light to set it to the spec for the engine you have.

I replaced the ICM so now I have spark the engine is backfiring when cranking how do I fix it?

Make sure the distributor is installed correctly, then verify the plug wires are in the correct order and check the base timing as stated in my earlier post. Did you get it to turn over with the key now?

(In the cap I wire up counter clockwise 1 5 4 2 6 3 7 8 is that correct? I'm not sure is it a 302 engine how would I know? do I need to remove the valve cover to see is the intake and exhaust valve close on number one cylinder? do you have and image showing how to do this? what number do I set at on the harmonic balancer? I see (TC, 10, 20, 30).

If you look up the VIN number online it might tell you what the engine is. Without that info the rest of your question cannot be answered correctly. Except for the question of finding TDC. You can do it the way I posted above, remove the plugs then rotate it while feeling for the compression to push out of the plug hole. Then you can set the distributor. No reason to open the engine.
Once that is done you can set the firing order as it is different for the engine types.
So look at the 4th digit in the VIN to find the engine series (IF it is the original engine) VIN G = 302, VIN H = 351, VIN S = 400 and VIN J is the 460. The firing order you have is correct for the 302, the 400 and the 460 engines however the 351 uses 1-3-7-2-6-5-4-8. Then look at the chart I attached and find the engine and the proper timing.

I got the engine started and running but it don't want to Idle unless i turn the high Idle screw all the way in and when i press on the gas pedal it seem to have popping noise like a back firing. and while the engine is running oil is pouring out around the fly wheel at the back of the enine. where it could be coming from? is there a sealed back there?

OOF, not a good thing, The misfiring is likely that the timing is still off a bit, adjust it using a timing light, The oil pouring out the back is not a good thing, it means the rear main seal has failed. On that engine design it means the bottom end of the engine has to come apart for it to be replaced. What I suggest is getting a paper service manual for that truck. Then use that to go through the engine. If the rest of the truck is in good shape. Or see if you can get a crate engine to fit it if a rebuild is more than you want to do.

I did use my timing light and adjust the timing to 8° at the harmonic balancer. the engine has been rebuilt so the rear main seal been replace unless it got damae replacing it.

If it's leaking like that it's damaged and has to be replaced. Stinks but has to be done.

is it possible to buy a defective real main seal? how does the starter switch work? no cranking when turn the key. the starter switch have a (I) and (R) on it. but only 7 volts at the terminal how many volts should be at the terminal?

It's possible it is defective, it's also possible it was damaged on install or that there is something wrong on the crankshaft allowing it to leak. No way to tell until you can remove it and check the parts. Please ask the question about the starting issue as a different question, we try to keep issues as separate questions to make later searches easier.