After some searching around, it appears that there is a new configuration for the USAF RC-135W's that is identical to the RAF RC-135's of which the first has recently been delivered.
Judging by the photos in this Kadena AFB spotting blog:
http://rodn.blog.fc2.com/blog-date-201304.html going all the way back to April 2013, there are now a couple USAF RC-135s that are now sporting this new configuration which removes the larger overwing wingtip antennas and adds a different antenna array on the top of the fuselage as well as what appears to be a satellite dish dome towards the rear.
The good news is that you can get the new model here:
http://www.militaryaiworks.com/newforum ... 68&t=14007
It's the RAF Rivet Joint model so all you need to do is use it in your Offutt AFB RC-135V/W folder. Either change the aircraft.cfg model entry or rename the model folder to something else.
I'm too lazy today to go back and figure out which serials so far have been given this upgrade.