What is the difference in the New Generation of Nightforce 1-4 NXS?

[jimmyp]

I understand that Nightforce released a new generation of NXS 1-4 scopes last year. How do you know if you are buying a new generation or old generation and what are the primary differences in the two?

[jimmyp]

It looks like there are a lot of readers but no posts so I will assume that a Nightforce NXS 1-4 inspected in March of 2007 is the most current model available!:)