I have a 2003 chevy silverado 2wd 4.3 v6 automatic, about a week ago my truck died on me and when I tried to start it back up it made a terrible grinding noise and never turned over. Towed it back home, checked my starter to see if loose and took it in to test and passed. Checked my battery to see if it was low and got it charged, still nothing. Took off the starter, teeth seemed to have same wear pattern but nothing significantly bad. saw uneven ware on the flywheel ring, maybe I should shim the starter or service the flywheel. Looking for second opinion, thanks

 

I won't swear to it, but I thought I had seen some threads talking about warped flex plates (aka flywheel)
Here is a Youtube of someone looking to resolve a similar issue....
seems like a good way to see if the flexplate is bent or warped...
Yes he does have the TC un-bolted from the flex plate for his troubleshooting...