Quoted from metallik:Some TZs came with it, most without.
Story I heard was that complaints were coming in of too many pops -> left outlanes when the machines were on test, so Pat added the posts and rubber to stop that. Later, complaints changed to too many pops -> SDTM off the new posts, so they got phased out pretty quickly.
I think most samples and some early production games have the posts, a few following have playfield holes but no posts, and eventually the holes got removed.
Agreed on everything except the post were given as an option to be installed or not. That’s also explain some differences and complicated things.