On my 70 Satellite, what are these 3 square holes on the front grill piece used for?

There are metal tabs that attach to the bottom of the grill...those metal tabs pinch down into those slots...

Do you know if the metal tabs are sold separately?

I put a new grill in mine back in 2009...The tabs came on the grill so they're out there somewhere...

https://www.ebay.com/i/401670383342?chn=ps

Simple Google search...

Its a plastic tab, not a metal one . . . the tab is screwed on the bottom of the grille and then it "slips in" and holds in the metal of the grille piece you have shown . . . however, lot of time the plastic tab needs a bit of help to "hold" into the metal - can use a small wooden wedge to spread the plastic tabs apart to hold better in the metal . . . .

Can see the tabs on my grille in this pic if you enlarge it a bit . . . .

Cheers

Mark

Ok Thanks

Well....having owned my 70 Roadrunner for a loooooong time, I will say this. The original tabs are half-plastic/half-metal. I got some reproduction ones with a reproduction grill hardware kit & the reproductions are all plastic.