Finally got my starter rebuilt and back in the car just to have my excitement stomped by this terrible sounding grinding/scraping noise. It ran for a few minutes as it should and then the noise started, and it only makes it at idle. Anyone have any ideas?? My car’s a 5L 5 speed.

 

I'd be taking that starter back out and having a close look at the gear , if it's chewed up you likely didn't shim it properly when you reinstalled it . And yes , even if it's the same starter , having had it "rebuilt" which usually involves replacing the "bendix" (overrunning clutch) , does indeed require the "shimming" process (setting the gear clearance) to be done as if you were setting up a brand new starter in it .