Grey 3/4 ton Hubcap - WIW?

[Ironhorse]

Have seen this style cap in both a white/black paint combo and in the stainless/black combo. Never ran across this style cap with what looks to be a factory(?) grey paint. No evidence of a re-paint, shows normal wear, light scale on the back side, no dents, some very minor dings. Also the center protrudes out some what, is not indented or pushed in like normally seen. Tried to show in the side on pic but hard to pick it out. Original application and a value would be appreciated.