V8 intake plenums use a T40 bolt (5/16"-18 x 1.25") in the center right position (passenger side - the photo was taken with the hood removed). Most bits are too large to fit, so either a long bit is required, or some of the casting can be ground away.
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The other bolts are 5/16"-18 x 1.5" with 1/2" hex head, integral washer, and ~1/2" unthreaded shank. Some have a ~1/2-long stud on the head.
