Thread pitch for bed holes

[ShadowsPapa]

I found it was easier to drill and install rivnuts where you need them.

I did both - I chased the threads in the factory spots, then I drilled and installed rivnuts in between.
The problem is - rivnuts aren't nearly as strong in the aluminum walls as the factory spots. They can pull out far more easily so you need more of them.
I used the factory holes as the primary points, and the rivnuts as extra security due to the spans between the factory holes.

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