[MikeyMo]

Hello Everyone,
I have a 07 Duramax CCLB 208k Bone stock. Started seeing “range shift inhibited” a few times, shifted from D to P, back to D no issues. Driving Monday heard spinning whining gear mesh /unmesh sound. Neutral only. Trans fluid good, religiously change fluid /filter.
I have internal NSBU. Is it worth changing ? Also 2771 code. Please advise, Transfer case ? NSBU?, ??
Thanks

 

[BoiseRob]

Are you the original owner?

 

[Mike L.]

Transfer case.

 

[MikeyMo]

Are you the original owner?

2nd owner, purchased @ 67k miles

 

[Ron Nielson]

Take a look here: P2771 - Chevrolet Diagnostic Trouble Code (DTC) Definition, Causes and Diagnosis