Found this bit of text in an article at USA Today...
"Toyota spokesman Bill Kwong said he doesn't know how many engines were made and installed before the flaw was detected. But he said the problem was found early.
It was fixed at the subcontractor's factory in February, the same month Tundra was launched amid a $100 million ad blitz."
Source:
Toyota fixing engine failures in new Tundra truck - USATODAY.com