First off, I cannot share scans of the scripts for free. Please do not ask. I am bound by a promise to another person, and the scripts were very expensive. I cannot and will not give them away for free. If we would ever get people who would be willing to pay a fair price for copies, then we could get a return on our investment and more people would be able to read them.
One of the scripts is called "Reasonable Doubts." This script is for an unfilmed episode from the fourth season. The fourth season was cut short due to one of the production companies pulling out, so only part of the season was filmed.
Here is a short summary of the events that occur in this script:
The Monterey stagecoach that is carrying the garrison's payroll is ambushed by bandits. DeSoto and his men arrive just in time to hear the wounded coach driver regain consciousness briefly and accuse a wounded passenger, Domingo Cano, of staging the ambush. The coach driver dies seconds later, leaving DeSoto no chance to question him. DeSoto assumes that Cano is guilty and plans to hang him the next day. After Don Diego hears of the arrest and planned execution, he decides to investigate. As Zorro, he frees Cano and quickly searches for clues at the scene of the ambush while pursued by DeSoto and the soldiers.
That is an incomplete summary that I wrote a long time ago, and I do not wish to pull out the script and try for a more complete one. My general impression after reading this script is that it would have made for an average episode.
Following is a scan of the first page of the script. Click on the image to see a larger version that can be read more easily.

Look for information on another unfilmed script in an upcoming post.
Note: Many of you are posting as "Anonymous," which I currently have enabled on this blog. I am kindly requesting that you add your initials or some identifier to the end of your comments. When the comments posted are by Anonymous, Anonymous, Anonymous, and Anonymous, it makes it hard to know how many people that represents. I really don't want to squelch the discussion, but I will change to Google ID required within a few days if necessary in order to force people to be counted as separate individuals. This would not affect any polls, but it would require you to create a Google account in order to comment. Thanks for your understanding and cooperation.