LUVTruck.com

I have fuel and air but no spark. I know the distributor might be bad, but I don’t know how to check it, and there is a blue cylinder connected to the distributor by a spark plug-looking wire, I dont know what it is

That is the ignition coil.

These trucks use a points style ignition. Points are a maintenance item and it’s a good place to start looking. Make a note of the orientation of the distributor cap, take it off, and see if the contacts are burned.

Also check the voltage to the positive side of the ignition coil.

Here’s a decent video on setting the point gap if it turns out they do need to be replaced. This is for a different engine, but the method is the same.