Recently I posted an article about a Simon & Garfunkel performance during a Frank Zappa & The Mothers of Invention concert in Buffalo (NY). There has always been a lot of discussion in which year this had taken place and if it did indeed. Even Mr. Zappa himself places it in what now seems a wrong year (1967).
Well that ‘mystery’ is now solved,with many thanks to the library of the University of Buffalo. The perfomance was not intended, S&G were just around and Frank must have agreed to add them in the show.
The show took place on May 2nd in 1969. In the Univeristy newspaper it was reviewed.
As soon as I receive that review I will ofcourse post it
Paul Simon - 'Time it was...it was' 
Wow! I think it’s kind of amazing they were able to “trick” the audience as late as 1969. Thanks for all the work you put into this site!