Valve Covers

Supercharged and naturally-aspirated engines have slightly different valve covers to account for the injector bosses located in the heads or the lack thereof.

Below is an image of the L67 valve covers. L32 valve covers would be the same design.
Note the cutout for the injectors on the top of the covers:

Note the smooth edges without cutouts for the injectors.

Most vehicles came equipped with fiberglass valve covers with the exception of the f-body vehicles. F-body's were equipped with aluminum valve covers.