i have a 1988 s10 with a 350 in it. just put a rebuilt starter and tranny in the truck along with a new flex plate. and now one week later the flex plate is ruined again. and i have no idea why its chewing up the teeth.
when firing up the motor with the new gear i didn't need to shim the starter is sounded fine every start un till just wouldn't start again. when i jacked up the truck i could see the teeth were ruined.   if any one out there has had similar problems and know a soltion please let me know. if easier my email is jonathonknock@hotmail.com  

You need to shim the starter.