All Nissan Titans come with an open differential. If you purchase the offroad or the pro4x package you can get an electronic locking differential..but it will only work in 4LO but it can be modified to work in 2HI or 4HI.
That being said Nissan does use an electronic system to try to emulate a LSD.
This system is called ALBS(Active Brake Limited Slip) It uses the ABS sensors to detect wheel spin and will apply the brakes on the spinning wheel in an attempt to send power to the other wheel via the open diff. This system comes on all 4WD's and can be purchased as an option on 2WD its called the Trac package and comes with tow hooks:soap:
ABLS is amazingly effective , I tried it extensively on snow/ice last year and was quite imppressed. A GMC with open diff, was stuck on a light patch of snow in our parking lot at work. I then put the Titan on ice 20 times, and walked off it everytime! It does a great job for the average consumers needs.
But now I have had the Detroit Truetrac LSD installed, and am loving it!