The plastic buttons, used with the 6.5 rocker arm assemblies, came up recently here in our forum, and that reminded me of a photo member MJ McCarroll sent to me some years ago.
As I recall, MJ used a specially hardened tap to thread the holes that were used by the plastic buttons., then added bolts and brass washers.
My experience with the factory plastic buttons has been a good one. I've not had a problem, though I do replace them whenever I do cylinder head work.
Through the years, I've heard from a couple of 6.5 owners who had varying degrees of problems with plastic button breakage. In one case, the buttons kept breaking even after replacing them... I suspect the root cause was a problem with the valve train that was causing the breakage (i.e. bent rocker, bent pushrod, bent valve stem or something other).
I liked MJ's idea, so I thought I'd show you all what he did. Thanks MJ!