Rust removal and prevention

[Soup DeVille]

Finally got the boards back on.  The brackets came out nicely.  I bought new galvanized hardware and coated it in grease before reapplication. 

One question; 11 of the 12 bolts went in and tightened properly.  The 12th bolt just spins in the hole.  They are 3/8" bolts.  Any idea why/what I can do?

Are you screwing into a captured nut, or is it a welded on boss?

[Submariner]

I believe it's just a screw hole.  I can't see it due to clearance issues, but two people who extensively work on these trucks have mentioned in the past that there is no nut inside, nor does it feel like there is one.

[Soup DeVille]

If its just slightly stripped out, you may try putting a couple wraps of teflon tape on the bolt to see if you can grab any of the remaining thread.

I'm assuming this hole isn't in a good place to get a tap into?