I'm almost positive they are ALL plastic. If you can fabricate , you can do like the mini- trukin guys & use a metal trailer fender for part of the assembly & fab the rest.
Of course, plastic can be painted after proper cleaning , prep & adhesion promoter. That,s what most car bumpers are made from.
I'm personally in the middle of fabricating an under hood cover to look like my hood using the sides of a fiberglass hood to cover the fenderwell area to near the engine. Will post thread when I,m further along.
PS post in the body section next time.
I have a '78 Pontiac Grand Am front clip and it has metal front inner fenders. 1980 was when (I believe) Pontiac went to plastic inner fenders. I would think that the '78-'79 Malibus had the metal inner fenders too!
I think all Malibu/El Camino`s have plastic,, the Buick, Pontiac and olds have metal inner fender wells,, all Malibu I have pulled have had the plastic,, there are new fiberglass ones,, you can buy and make look better than the factory plastic ones,, Matty man