The following will examine a link between the 'corrected' sixth line of the 340 cipher and the Exorcist letter symbols. The Dripping Pen card and 340 cipher were mailed to the San Francisco Chronicle on November 8th 1969, with the Exorcist letter, widely considered to be the final Zodiac correspondence, mailed just over four years later on January 29th 1974 to the same newspaper. Is it possible a link could have been generated by the killer over such a period of time.
In the image top right I have moved the two symbols on the extreme left of the Exorcist letter to the right side as shown without altering their position on the vertical axis. Then I have turned the extreme right symbol on the Exorcist letter 90 degrees clockwise to form the new arrangement, shown in the bottom right image. This can now be compared to certain characters on the fifth, sixth, seventh line of the 340 cipher. The area in the proximity of the corrected sixth line. Five of the six characters on the Exorcist letter now bear a noticeable similarity to this area of the 340 cipher.
The i looking symbol under the K, would be represented by the blacked out region in the 340 cipher. If this was placed into the cipher it would spell the word PIG vertically. Close to this are the FK letters. In the 13 Hole postcard mailed on October 5th 1970 the Zodiac Killer would use these two letters again, as well as the word pig once more. Pasted on the postcard upside down were the words "There are reports city police pig cops are closeing in on me. Fk I'm crackproof. What is the price tag now?"