I take it that no one actually knows the answer. Even the ultimate guide book by J. Kielkowski (K2 and the Northern Baltoro Mustagh) is showing Fritz's route going up and around the corner, beyond which is the upper end of the Hockey-stick Couloir.
I trust Wiessner, but I also wonder whether Pasang Lama ever read and confirmed the claim that they reached 8380 meters after that left traverse. Yet, in any case, I suppose that only Fritz had an altimeter. And do not take me wrong: unquestionably, Fritz Wiessner is a great hero.
Mike m: You do not need to find the book, just try to remember its title or its author. That would help a great deal.
By the way, it must be said somewhere that JIM CURRAN (in his book: K2 - The Story of the Savage Mountain) has messed it up a great deal saying that BARRRY BLANCHARD et al have partly repeated the Kukuczka-Piotrowski route. In the AAJ (1994, p.246) Barry states clearly that in 1993 they followed the above-mentioned route to just above the serac before they traversed right to the Cesen spur. In other words, they hardly entered the immense south face. I do not know where this misunderstanding originates from. Here is the quote from Curran's book, which is completely false: