Have searched the site and other forums but found nothing on this. I rebuilt the nv5600 myself because turn around time was 3 weeks everywhere I looked. Took me about the same time with everything else I had going on but saved $700.

When I bench tested after reassembling the transmission, I had all 6 forward and reverse. Put it in the truck, no reverse. If you roll the truck slowly and feather the clutch, you can get a little closer and it will trigger the reverse lights for a second, but then it will grind and will never actually go in. Has anyone come across this? I was as careful as I could be when putting it back together to make sure everything went back the way it came out. Replaced all outer bearings and all but one set of synchros. Every other gear engages and is quiet.

 

Might be something as simple as something on your shift lever assembly keeping you from fully engaging.