Nav unit install

[GM_Tech]

2003 model H2's will work only with Lux Model Navigation Radios.
2004 & up will work only with Non_Lux Radios (does not matter if you have Y91 option or not)
Some 2004 models (very few ) that were manufactured on 2003 may need Lux model Radio
If You install nav radio in 2003 and need vin # to be reprogrammed by dealer, most likely they may tell you that they don't see that option in their Scan Tool. what they have to do is, on their Scan Tool they need to select 2005 as a year built

Y91 ---> Merchandised PKG - Luxury Edition
Has nothing to do with Navigation Radio

Hope this info will help