[mr48chev]

Rebuilt starters are usually the ones that need shims and the more times they went though the rebuilder the thicker the shims they need. After they take the starter apart and clean the end frame they run the surface across a sanding belt to slick it up and every time they do it it takes a bit more metal off it.

One thing, scrape that paint off that mounting surface where the starter contacts the block before you bolt the starter to the block. Even if you have to hold the starter up to it and trace around it with a sharpie and then only scrape the contact area if you are anal about the paint. That way you aren't posting and asking why it won't crank over good with the reason being that paint is insulating the starter from the block.