Oem bed rail questions

I’m selling my OEM tonneau cover that works with the oem bed rails. There’s a potential buyer that has 2018 but doesn’t have bed rails and does not appear to have the threaded holes in the bed side for the rails. What’s his options? Drill and Tap the holes?

 

The holes are there. Does he have a spray on liner? It's under there. Poke at it with an awl.

 

https://www.tundras.com/threads/diy...aper-option-than-oem.1906/page-5#post-1223172

 

Thanks, zooming in on his pictures I would agree they are there. Any idea what the thread specs are on these?

 

M6-1.0

 

Any idea on length?

 

I got 20mm long bolts. I hear 16 works too, but there's plenty of room back there for the extra.

 

Thanks, much appreciated