You may be missing the filler pieces that the factory put in there. They were screwed to the firewall and extended toward the fenders with anti-squeak material stapled to the edges. The pics shows what's left of the originals on my truck. One side was basically rectangular and the other L-shaped. Replacements are available from the usual vendors.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
