Did you look at the RigRite website (
http://www.rigrite.com/spars/isomat_spars/ISOMAT_Main.html)?
Looking at their website, it appears that I may have the "Old style NB-26" Gooseneck assembly and NG1 gooseneck bracket on my Kelt 760. Not sure if the new style NB-26 and NG1 are a direct bolt-on replacement.