I have an older tandem axle grain truck with a Eaton three speed air shift in the rear axles.  Low range jumps out from time to time and I'd like to tear it down and repair it.  I haven't had any luck finding info on the net.  Am I wrong in assuming that the problem could be in either axle?  It looks like the rear axle must shift at some point as the front one does?  Any input and a link to a parts diagram would be helpful.
Thanks.