Four wheel drive shifting

My truck would not run on two wheel drive, it would shift to Four wheel drive auto and would have a grinding noise when shifting to two wheel drive and after one mile would disengage, then I would have to switch to Four wheel drive auto.
(runs on Four wheel drive auto and Four wheel drive low, will not run on two wheel drive and Four wheel drive high).
Replace the selection switch buttons on the panel, replace the transfer case module control and still the same problem. Took it to a transmission shop and had the transfer case disassembled and they did not find any thing wrong, had the transmission overhauled and still the same problem. Now they have replaced actuator motor assembly and the problem is reversed; (runs on two wheel drive and Four wheel drive high and will not run on Four wheel drive auto and Four wheel drive low). You input to address this problem is greatly appreciated, the transmission shop guy are scratching the heads. Thanks for your help.