Attaching plastic grille to the surround

[Accelo]

I finally got around to attaching plastic grille to the surround and ran into some issues. The rectangular holes, for the retaining inserts, are not the same width. Some are so tight the nylon insert will not go through the hole and others so loose they fall through even with the screw installed.
The top slots were. .255-.252-.268-.313
Bottom slots are .330-.320-.320-.330
The nylon inserts are all the same at .310

I plan on using a file to widen the narrow slots. Unsure what my plan is for the loose ones. I am able to work out the inserts by hand with the retaining bolt installed into the insert. I will have to figure out something to keep them from rattling.
Just a testament to the great job GM did on the trucks originally.
Wonder what a complete aftermarket truck would look like if the parts were left as delivered.