My 05 3500 will not shift out of 2 hi,When I select 4 hi the lights flash 2hi,4hi,4low then the red nuetral light comes on. I changed out the shift motor, now when I select 4hi the amber light for 4hi flashes for 10-15 seconds then goes out, the green 2 hi comes on. after several cycles it still wont shift.
Thoughts? Recomendations?

 

I had a shift motor issue on an 06 last year. It would start engaging itself into 4h CONSTANTLY with no indication but you could surely tell that it was engaged on tight maneuvers. It got to the point where the truck could be parked, off, and locked and you could hear the shift motor cycling. It actually did its best in the final stages to try to force an engagement to 4 LOW while at road speed!!
I hoped to not just start throwing parts at it like crazy so I asked the dealer to diagnose it while in for the steering recall. They were 50% sure it was the shift motor and 50% Totally Integrated Power Module (TIPM). With some other small erratics taking place brought into the talks, they were 90% sure it was the TIPM. Their price was disgusting so I ordered a Dorman TIPM from Summit (oddly enough they had this). Changing the TIPM did not do it for me so I had to Still change the shift motor. I bought a brand new OEM from eBay for greatly cheaper than the dealer.
On mine, the shift motor is what fixed it. It apparently has sensors of some sort inside of it so if it doesn't detect an engagement, it will keep trying to engage. Did you buy an OEM shift motor or aftermarket?
Maybe in your case (if your model year uses it) it could be the TIPM. many people have had issues with them. It apparently integrates your entire electrical system like an all knowing brain/ body/etc computer. Mine is a big black box (fuse box) by the drivers side battery. There are circuit boards under the fuses in the same box.