Truck will not start?

It cranks but won’t start. I didn’t check the flex plate, replaced the old one in Oct. 2022 so I figured it’d be good. But I’ll check it out tomorrow. I cleaned up the starter and reinstalled it earlier, truck fired up on the first try. Then went to leave la little over an hour later, doing the same thing again, cranks but won’t start.

Okay, so there seems to be less power trying it this morning. There are metal shavings in the flex plate housing as well and the teeth feel really rough on the edges. Of course, that’s where it’s coming from, where else, right? Thinking too hard about this probably. Looking at the starter on my workbench right now and I see the plastic on the solenoid is cracked. I’ve had a starter crack before, but it was on the nose, around the gear. Also, Idk if this is an issue, I feel like it is so I'm going to tell you about it. The starter doesn’t meet up with the bell housing. I’ll post pics. The first pic of this shows the starter with a spacer, the second is without. I can’t seem to find anyone that: a) has this issue; or B) has heard of it or has a suggestion as to what a solution could be. I’ve tried finding a spacer of sorts to fill in the space but so far, I haven’t found anything that works.
Thanks man, your helps appreciated.

Do you know if the starter is supposed to be a direct drive or if it's the gear reduction starter? Does it matter? I have been replacing it with the same one each time, the direct drive starter, and I called to have the part numbers cross referenced, they match up.

I checked the teeth on the flywheel again, they are rough on both sides.

I just got off the phone with the transmission shop where I got mine installed in January and when I asked if they noticed any damage to the teeth on the flywheel while under there, the secretary said there were no notes about that on my service tag and that they would have definitely noticed. Not sure if that pertains, just trying to give you as much info as possible.
Thanks again.

Another update, I called and spoke to a mechanic at a GM dealership and he says the correct part OEM part # is 10465389.

Okay, so I cross referenced both part #s. The # given to me by the GM dealership mechanic matches up with the starter that I've been buying over and over. It's a direct drive with 9 pinion teeth. The part # you gave me is a gear reduction with 11 pinion teeth. Yesterday I swapped out the old starter for the same one I had been getting, #10465389. Installed it and tried to start my truck up, only to have a different issue arise. The motor is turning, but I think slower than usual, and it's making a noise that sounded to me like the battery needed to be charged. Charged it up for a few with jumper cables and tried to jump it but got the same outcome. I'm going to swap out the starter again for the #10465167 later today. I'll get a video of what it's doing now and post it as separate reply on this thread first though.

Thanks

Okay yes, turning a lot slower than it should be. Windshield wipers work when the key is in on position, so the battery is not discharged, there’s no corrosion at the cable terminals and they are nice and tight. I should check the wires in the starting circuit and ignition switch next I suppose?