Looking at buying NBS Hoe/Kon; questions

[adriver]

2004 Tahoe owners manual.

 

[Thouse]

Here's a pic of the truck in question... Wth?!

EDIT: NR4 TRANSFER CASE ALL WHEEL DRIVE (AWD), OPEN DIFF, TWO SPEED
Looks like an even more rare xfer case. Probably want to stay away is my guess.
I just dont understand 3 button selection tho. Can someone explain?

EDIT 2: https://www.gmtruckclub.com/forum/threads/4wd-or-awd.84126/page-2

Just curious why would it being rare make you want to stay away from it? Is it because parts would be less common?

 

[live2pull]

In general, the AWD system will be more expensive to maintain would be my guess.