Andy,
Both guides you referenced were only partially correct. I am suspect they were keying on the original license. We do know that,

• the International opened in July 1969 with a new rack.
• The International did change its' name to Hilton International in Feb 1970 with a new rack.

It seems to me that the authors went right from International to Las Vegas Hilton bypassing Hilton International, If any of the authors know why, please post.

Forgive me for asking a test question without knowing the answer, that is why I titled it Test the Experts so we could all benefit from the pooled knowledge.