I've used both and the fiberglass one is closer in appearance to the original because of the too-glossy finish on the ABS version, but both have their pluses and minuses. The insulation is separate on the f/g version which makes it easier to work with in creating the required holes and the semi-circular sections where the instrument panel attaches to the firewall. I recommend that you buy the version without holes as the some of them are misplaced on both the B and V-8 versions of the ABS product, for example.