I've got those same valve covers on my 5.8. They were always advertised as having the ford racing chrome oil cap. Mine came with that same huge black cast aluminum monstrosity too. I pried it off the cap and guess what was underneath? No, not a chrome one. A regular black plastic oil filler cap. They must have run out of the chrome ones or just got cheap on us.

 

Folks always say a few stickers from aftermarket part manufacturers in the back window are good for 20 hp, I figured I doubled that with those valve covers. Outside of cleaning everything up that was my only dress up item but they really add a nice touch.