how do you know what transfer case

[YNOT]

how do i know what transfer case i have in my 2001 tahoe? i need to change the oil.
thanks.

[scott99zx6r]

Take a peek at the rear of the case. There should be a tag on it, usually round and it will say np231 for example on it.

[YNOT]

i looked, the sticker said use AutoTracII, so i'll have to go to the stealership on monday.