Undercover, You are right, I looked also in the King James version (sacrednamebible.com), the tetragrammaton is mentioned there in Joel 2: 32.
This contradiction actually supports that the hebraic God Jehovah are Jesus, which some people believe.
There is a scholar named Rolf Furulli that supports the NWT.
Thanks for your watchtower reply, as usually the GB puts alot of interpretation into a simple matter. Focus on the phrase in Acts 4: 12; It says; there is no salvation in anyone else, .... The conclusion: Jesus is the only Saviour.