Looking at this picture, (disregard the red lines at the top) from the center of the grommet on the upper right side to the edge of center cover where it bolts onto the firewall (which is the left side or driver side of the car when it is mounted) would be 16 1/8" and the left side of the picture using the same description, grommet center to engine cover edge would be 9 1/4"
If you take a measurement using the same approach from the grommet center stopping at the edge of the steel on your cover, subtract the 2 and you will have the gap size needed.
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