91 Mustang Gt Fog Lights Are Too Small

Hi. I bought a 91 GT not too long ago, and it was missing the fog lights when I got it. I ordered OEM size fog lights for it, and they're about an inch too small in diameter for the bumper. I've searched all over the internet for an answer for this, and I'm coming up with nothing. The bumper cover appears to be OEM style, but it's definitely been replaced at some point. So I know it's not the original bumper cover, but I'm just wondering if there's some sort of bezel that goes in there or something. Or are there some cheap bumpers out there with holes that are way too big?

The holes on the bumper measure 5 3/4". The lights measure 4 3/4". I don't have one to compare it to. There aren't any other fox bodies around here. That's kind of the reason I bought it.

So it's supposed to have a half inch gap between the bumper and the light?