Has the motor jumped timing?

slantsixdan said
That is a Lean Burn carb at least. It might also be a feedback carburetor. Post a picture of it, and check the rear face of your exhaust manifold's central collector area; is there an oxygen sensor in it, with a single wire going to it? Either way, a Lean Burn-to-conventional changeover involves the carburetor, too, not just the distributor.

Does this vehicle still have its catalytic converter(s)?

There are many ways this can go badly. It's tempting to use the hole that comes pre-drilled in the new distributor gear, but that's wrong; it has to be done right. And reinstalling the distributor sometimes requires patience and persistence as well.

It's not a bad idea to check for a slack timing chain, but you already know the truck quit because no spark, which means unless you have terrible luck and the T-chain jumped at the same time your ignition system failed, you can pretty well rule out a sudden T-chain problem for now.

I do not see an oxygen sensor on the exhaust. At the back of the manifold it has the pipe coming around that went to the anti backfire valve and then went to the EGR pump or air pump or smog pump.
We have blocked that off and eliminated the air pump.
It still has a catalytic converter but the converter is not plugged.
As for installing the new distributor gear the gear came with a shim and only one side of the gear was drilled so therefore we shimmed it and drilled it. I am not in a position to where I can get a picture of that carburetor or the motor at this time.

Prior to losing Spark the only way we could get this motor running was at 15 before top dead center. So there was something wrong with it prior to it losing Spark. And it still had the computer in it at that point.