Distributor off 1 tooth effect crank sensor calibration?

Had trouble getting 00 Astro 4.3L to run. Shop said timing was off and asked if I had taken out distibutor? I did not. They got it running but I later found I had a 1336 code (crank sensor calibration needed). Had this calibrated by a shop with GM scan tool (snap-on tool at 1st shop could not calibrate it). Now getting a 1345 code (crank to cam correlation timing). Set engine to timing reference marks and found distributor off by a tooth. Put in correct position, still getting 1345 code. Does the crank sensor need to be recalibrated again?

Now getting a 1345 code (crank to cam correlation timing). Set engine to timing reference marks and found distributor off by a tooth. Put in correct position, still getting 1345 code.
Wouldn't crank to cam correlation mean the timing chain jumped a tooth? That would explain why the distributor was off. If so a new timing chain set is needed.

Possible...but it only has 80k miles on it. Since the ingnition timing is controled by the ecm, wouldn't I be able to continue to advance/retard the distributor position (moving a tooth at a time) to see if the code clears? I know it would be the tail wagging the dog, but it would eventually put all in the correct relationship. Wouldn't it? If this would work it wouldn't it be a lot easier than accessing the timing chain for inspection.

The problem ended up being the rotor mount (used for cam sensor timing) had shifted @ 35 degrees. Looking back I believe I caused the problem to begin with. I was trying to get the distributor in to position so that I could remove the cam sensor. I had loosened the cam sensor mounting screws, but the distributor was not in the exact position to remove the sensor. I bumped the ignition a few times to get it into position and the rotor mount (pressed on distributor shaft) hung up on the sensor. Who says you can't adjust the timing on a 4.3L!!! Referencing a GM troubleshooting guide, it showed the pulled distributor with the paint mark and dimple aligned & having the rotor @ 7:30 position. All is well for the time being.