I don't know what year, but there was another incident where a rider came off, wearing two piece leathers, and as the rider slid on his back, the leathers rolled up. That resulted in the rule that the leathers have to be one piece, or zipped together.
I, too, enjoyed the pictures on the site mentioned above. I think one of the pictures shows Marty Dickerson's Vincent Rapide, with the Joe Simpson Black Lightning right behind it.