Nv263hd Won't Shift Into 4lo Or N

[chopperguy_tx]

Hi all!

Have a '04 GMC 2500HD 6.0L/4L80E/NP263HD, just had my transfer case rebuilt, and now I cannot get 4LO or N. 2H and 4H are smooth as butter. When selecting 4LO, the 4LO light flashes a few times, you can hear the shift motor try, but can't get it. When selecting N, I get the N light, but the transmission still functions in all gears (including refusing to roll in P).

Shop is saying shift motor/encoder needs replacing and only way to check is to swap it. Am understandably hesitant. Have read the numerous threads about encoder replacement and/or dash switch, but short of swapping parts I'm a bit stumped on where to go from here. Help with the following is much appreciated:

 

1) Is it possible the shift motor/encoder decided to go nuts, and create my transfer case implosion in the first place?

2) If i swap the shift motor with a reman unit and that's not it - what do you think my odds of being able to return it with 0 use?

3) Since the truck is driveable - should I roll up to a dealership and see if there's any codes thrown?

 

Just looking for some direction if y'all think the rebuild is at fault, or there could be other things afoot, and how best to go about it. Thanks in advance for your help!