Distribution cap spark plug order needed

Hi,

What size engine does the truck have?

Joe

As Joe alluded to, there are several engines for that truck.
The firing orders are
4.3L V6 engine - 1-6-5-4-3-2
5.0L, 5.7L, and 7.4L V8 engines 1-8-4-3-6-5-7-2
These are read looking down on the distributor cap and going clockwise in rotation.
The next thing is determining where the cap number one cylinder is located. This can actually be any of the posts depending on how the distributor was installed. As long as you follow the firing order.
The fastest way to find out which one it is, would be to remove the spark plug from number one cylinder, on all of those engines that is the first cylinder on the driver's side of the engine. Now use a ratchet or similar to rotate the engine over with a finger or similar item over the open spark plug hole. What you are listening for is air to start pushing past your finger. That indicates that the piston is coming up in the bore on the compression stroke.
Now remove the distributor cap and look at the front vibration damper to find the timing marks, line up those marks at TDC. Now look at where the rotor on the distributor is pointing. Place the cap onto the distributor and the post that the rotor is lined up with is cylinder one. Install the plug into the cylinder and run the number one wire to the distributor. The cylinders on those engines are all laid out the same but the V6 is missing 7 and 8. Don't assume that the number one cylinder is as shown in the image, if anyone has ever removed the distributor it could be wrong, that is why I suggest the process above. It removes anything like that from the equation.