The first thing to look at is the Phillips 66 Map crosshair with numbers around its cardinal points, the number 0 facing north, the number 3 on the east axis, the number 6 on the south axis and finally the number 9 on the west axis. It is easy to consider these as clock points, however the number 12 is replaced by a zero, so we will refrain from doing so. But what relevance do these numbers have, bearing in mind we are looking for a grid position on where the bomb is set and considering a clock face does not begin on zero. The Zodiac mentioned 'radians and inches along the radians,' we know a radian to be valued at 57.296 degrees, so all we have to do is travel around the circumference of his crosshair situated over Mt Diablo, by a fixed number of radians. Then once we have found the correct amount of radians, we travel away from that point, along the radian in inches, until we locate the bomb. But how many inches. The only numbers we have are the ones Zodiac placed around the crosshair, and these are situated along the radian line, so these are what we'll use to formulate the answer.
We have 8.2 inches, so with a simple calculation we multiply 8.2 by 6.4, to give us our distance to travel away from Mount Diablo.
8.2 X 6.4 =52.48 miles. In other words the bomb is set 52.48 miles from Mount Diablo at an angle of 246 degrees. But bear in mind the Zodiac stated "The Map coupled with this code will tell you where the bomb is set. You have until next fall to dig it up."
So the code of 32 symbols has to tie in with this location.
Below is a diagram with an angle of 246 degrees radiating from from Mount Diablo, you will notice it passes over the bold circle Zodiac drew and lands in the area of San Francisco International Airport. In fact it is virtually 52.48 miles on Google Maps to this location. Here is the area of South Linden Avenue, right next to San Francisco International Airport, shown as being 52.90 miles from Mount Diablo.