Horrible grinding noise

[JBU]

I need some advice.  I have a 74 eldorado that started to make a horrible grinding noise when I hit the starter button.  This is what has been done so far.  The ring gear is a bit worn but doesn't seem excessively worn.  My T3 had about the same wear.

Put in a new odyssey battery

fitted 2 different new valeo starters

Put in a new starter relay

With all of this done the grinding noise is still there.  Any suggestions on what to look for next?

[guzzisteve]

Try a different ring gear on flywheel, sounds like it's trashed from spinning teeth from starter. Why? not meshed, worn although looked to pass. Not much choice now, no magic shims to take up slack.

[JBU]

Thanks Steve, that was the next thing I was planning on throwing at it but wanted to check if there was anything else I might be missing.

[moto-uno]

 That's gonna be a lot more work , sure hope you find the 'smoking gun' if you go in there !  Peter