As I've always understood it, the guts of the boxes are very reliable. The problem is in the shift motor...if the unit is shifted properly (i.e. pull the switch, give the unit two seconds or so to pre-load the motor, then pop the clutch for a second for it to shift), all should be well, but IIRC one of the worst things you can do to it is to pull the switch and immediately pop the clutch...that makes the motor have to move the entire gear on its own, and the motor wasn't really designed to do this...and that'll result in a significantly reduced motor lifespan, and last I checked, finding a replacement motor isn't going to happen.
I wish that parts for these units could be sourced...
FWIW I have a second Doug Nash unit that I can pull the shift motor out and take pictures of next week; maybe you can compare that to what you know about the two-speed axle parts and we can figure out what can be used as a replacement. Let me know what you need to see...my spare unit's sitting in storage in L.A. and I'm going down there later this week, so I can get any info anyone needs on it over the course of that week...
