Thanks for posting those docs Dave. What is up now represents the totality of what we have on the FBI attempt, I believe.
No never found out much more about the San Jose letter. My FOIA and appeal were denied, consistent with someone in the letter still being alive, or could have been for other reasons.
We do have a thread on the San Jose letter. Interesting connection to Montana, and Morf and I looked for San Jose area murders.
MODERATOR
Thanks doranchak and others,
Special listings:
EDP for each character in Qc32 (340) and characters -9 to +9
EDP for Zodiac plain text, sorted alphabetically by words,
and words approx. -8 to +8
Stutter 2s and 3s in Zodiac plain text and decrypted message
What is EDP?
What is the Zodiac plain text? The letters that accompanied the 340?
What is the decrypted message?
What is meant by, stutter 2s and 3s?
If this is obvious, I’m really tired… 
What is EDP?
I thought that it might be "expected differential probability", which is part of differential cryptanalysis, but those techniques were not developed until the late 1980s, long after those FBI files mention EDP.
It may just be "electronic data processing."
For example, one excerpt says "EDP runs sliding word through messages except for impossible situations". Perhaps it just refers to using a computer to electronically plug plaintext words into the cipher text.
What is the Zodiac plain text? The letters that accompanied the 340?
What is the decrypted message?
My guess is they are referring to using the known plain text from Zodiac’s letters and the decrypted 408 as cribs in the 340, to try to unlock the 340.
What is meant by, stutter 2s and 3s?
I wonder if they considered "dummy" syllables of length 2 and 3. For instance, from "Decrypted Secrets: Methods and Maxims of Cryptology":
Dear doranchak, I am a spud at codes, a real novice. I have been playing around with your cypher cracking system and wondered if you could add a side function for us spuds, hope you can understand this… when I click a letter for a change it changes in the first instance the second time I change it I would like it to go to go to a quad box keeping the previous letters, Ready for a new letter alongside for a third and fourth letter, the reason for this is to allow for changes for the multiples of changes that can take place but keeping multiple possibilities alive rather than deletion. Maybe with luck it could bring about some with first and last letters being right with the middle jumbled, as you know they can still be readable. Obviously using what you know to be Ls and the like as your starting points. Just a thought don’t hang me.
Example
I cnduo’t bvleiee taht I culod aulaclty uesdtannrd waht I was rdnaieg. Unisg the icndeblire pweor of the hmuan mnid, aocdcrnig to rseecrah at Cmabrigde Uinervtisy, it dseno’t mttaer in waht oderr the lterets in a wrod are, the olny irpoamtnt tihng is taht the frsit and lsat ltteer be in the rhgit pclae. The rset can be a taotl mses and you can sitll raed it whoutit a pboerlm. Tihs is bucseae the huamn mnid deos not raed ervey ltteer by istlef, but the wrod as a wlohe. Aaznmig, huh? Yaeh and I awlyas tghhuot slelinpg was ipmorantt!
It may just be "electronic data processing."
For example, one excerpt says "EDP runs sliding word through messages except for impossible situations". Perhaps it just refers to using a computer to electronically plug plaintext words into the cipher text.
I found this: http://en.wikipedia.org/wiki/Electronic_data_processing
The modifier "electronic" or "automatic" was used with "data processing" (DP), especially ca. 1960, to distinguish human clerical data processing from that done by computer.
