1971 C10 starter issues

[Keno]

I just bought this 1971 C10 pickup, has a 350 engine 4 bl. automatic 350 with a/c. The starter is bad I've installed 4 different starters and it still isn't right.
Autozone # DL3510S nose sits to far back and wore out about 3/8 of the teeth on the starter. Took it back they give me a DL 3627S it looked closer sounded better but after 2 days the teeth broke off on that starter.

Bumper to Bumper looked it up and gave me a 25368 Worldwide rebuilt and it has done the same thing wore out the teeth about 3/8 in on the drive.

Now I've installed one from Advanced Auto P3508S Worldwide rebuilt and its just as bad so I'm sure it is only going to last a short time.

We've shimmed them in every direction possible and tried everything I know to do, I don't think we have gotten the right starter yet. I have even went as far as looking up the motor to make sure it's the original and heres those numbers VO331TBC.

This truck is driving me crazy and the sad part is it's all original with only 70,xxx miles on it!

The flywheel has some wear but nothing bad and it's not loose.

Any help would be greatly appreciated!!!

Thanks
Keno
e-mail salleys@cox.net