I have the 1996 silverado 350. I have a Haynes repair manual and have
done a few test. The problem was bucking but sometimes the truck would
run just fine. I had the ignition module checked at autozone. it
tested bad they said and i got a new one. However, the code came back
the next day.

I did all the checks on the coil with a volt meter. It checked good.
The ignition module, coil and crank position sensor all have 11.5-12
volts supply voltage. The ground wire in the harness has continuity to
battery ground.

Checking the ignition control module harness white wire with a
voltmeter on AC mode should yield "approximately"1.0 to 4.0 volts with
the engine cranking. It yielded 6.0 volts in my test. it says to check
the crankshaft sensor if the voltage is out of range. Backprobing this
sensor with a voltmeter on AC should result in "approximately" 5.0
volts. My test resulted in 3.9-4.0. The manual then says: "If a CKP
sensor signal is not present, replace the crankshaft position sensor."

Well, my voltage was out of the 'approximate" range, but a signal was
present.

It goes on to say if the ignition control module test and the
crankshaft position sensor tests are ok, to have the PCM checked at a
dealer.

This is my daily driver but the truck has 342,000 miles so I dont want
to spend to much at a dealer.

Where should I go from here? Replace the crankshaft position sensor? I
have read something about there being a "relearn" process that has to
be done by a dealer sometimes when replace ing this sensor? Could I
still drive it?

I really appreciate your help!