These have been repainted at some point and have some chips/ damage as seen in photos. No cracks or leaks. $100 obo

 

As a Corvette owner I would say that that is likely the original finish. These valve covers are made of magnesium and it doesn't get along well with paint. You might try posting them on the Corvette Forum in the C4 Parts for Sale and Wanted section. GLWS

 

I'm actually interested in them, but I am unsure of if they'd be a good fit for my '91 GTA. Stupid question: which side is which? Is the oil fill cap on front of the driver's side? Seems like a lot of centerbolt valve covers for our cars are the earlier version that has the oil fill cap closer to the firewall, whereas the later ones have it on the front.

 

If installed on a TPI F-body with the oil fill cap on the driver side these would be 1989 and down style.

Driver side will have the oil fill at the rear and PCV at the front. CCV at the rear and Corvette logo at the front on the passenger side.

 

The one with the emblem is for the drivers side so the oil fill is in front on the pass side. Drivers side gets the PCV and the pass gets the fresh air tube from side of the throttle body

 

On a TPI F-body it is super busy at the passenger side front of the valve cover with the AC compressor, heater control valve and coolant hoses, and A.I.R. diverter valve and hoses. Unless most of that stuff has been removed or rerouted it's not the best place for the oil fill cap.

 

Fitment wise, they're interchangeable from side-to-side; each cover will fit either side. But due to the bolt holes being slightly lower than the horizontal center in the covers, they can only be oriented one way, regardless of which side they're installed on.

Function wise, that means they'll be like my 87, with the filler cap in the rear on the driver side, the PCV in the front on the driver side, the emblem in the front on passenger side, and the breather in the rear on the passenger side. But they can also be installed like they're oriented in the first picture in post #1, with the filler cap in the front on the passenger side, the breather will still be in the rear on the passenger side, the emblem in the rear on the driver side, and the PCV will still be in the front on the driver side front.

Finish-wise, some years were painted like these for sale, and some years had a natural-looking cast finish, which looks nothing like the painted ones. And if the finish has deteriorated, people would use that "official" nickel paint on them, even the ones with the cast finish, instead of trying to restore the cast appearance. So when you see painted ones, they might've originally come like that, or they might've originally had the cast finish but are now painted. And some people have polished them like aluminum instead of painting them.

84-85 perimeter bolt valve covers have been reproduced. But 86-91 center bolt valve covers have not been reproduced. Used ones are easy to find, but good condition and NOS are hard to find.