Neutral Gremlins

[Fumes21]

I having some issues with the transmission in my 2006 GMC 2500HD Duramax (LBZ) 4X4. I drive along and it goes into neutral, I let off the gas (diesel), then step on the gas again and then everything is normal, you drive along for a few miles or more and it will do it again. Not sure why this is doing this, anyone can help?

[Bookumdanno]

Have you checked the transmission fluid?

[Fumes21]

No codes, oil is good, took it to an authorized Allison dealer, they replaced the 3 sets of twisted pair wires for the speed sensors (from the senors to the TCM).

They pulled out the rear speed sensor as when they had the computer hooked up to it was reading that the truck was moving and it wasn't. There were some scratches, marks on it, so they looked a little further and there was only maybe 5 or 6 oz. of oil in the transfer case, (no sign of any leaks either). So they suggested that the transfer case needs replacing as something is moving around in it.

So this is where I'm at now.