I didn't read this entire thread, but I did do a search for Morgan and didn't see any hits for a 1966 Topps printing variation so if it is posted already I apologize.
I was looking through my 66 set in my binder last night when I saw something on my Morgan card below the S in Astros...I took it out to see if I could scrape it off and saw that it was actually red print. I looked through ebay and found the exact print error on only one other listing. I searched google images and saw another like this.
here is the one on ebay
https://www.ebay.com/itm/19379652802...MAAOSwNTpf1DJH
Here is mine and a graded one I found in google images