The chronology of 1975 has a new conversion date based on some reasonable assumptions in regards to the 6000 years of man's existence. That's one thing the WTS doesn't bring up any more. This is a fundamental concept that if Christ is to rule for 1000 years within the last 7th Creative Day, which is 7000 years long, then we've run out of time in 1975.
But there are corrections. For one, the Exodus archaeologically occurs much later. The fall of Jericho by Joshua is dated between 1350-1325 BCE which means the Exodus 40 years later occurs at the end of the reign of Amenhotep III. Secular history via Manetho had always identified the Exodus at this time. Further, now that 1947 has occurred, if it truly marks the 70th jubilee week from 1947-1996 then we have a critical new absolute date for the Exodus in 1386 BCE. This date agrees with archaeology, Bible history and Bible chronology and even can be set by an astronomical text, the KTU 1.78.
JWs use their own timeline to date the Exodus to 1513 BCE which even RC14 dating from Jericho proves is way too early. Thus with 127 years of extra time to deal with, a new date relating to the 6000 years is now in place. It is not absolute, but it takes into consideration reasonable adjustments, the result being a conversion of 1975 to none other than 2011 AD. But this is speculative. Here's the video showing the details.
http://www.youtube.com/watch?v=5ALN7NVurO8
LS