Rear driveshaft not spinning, truck only drives with power diff locked

bad diff lock this is gonna be costly

 

Diff lock works , other wise you would not have made it home.
Your thru shaft that goes to the output on front rear end is broken.
Your power divider has to come out to fix that.
If it's got lots miles you might want to just put an exchange in it. You got to take the whole thing out anyway.

 

You are going to discover just how expensive it's going to be. I popped a machined gear that was about 14 inches long by around 3 inches thick with teeth cut the longitudal axis end to end. I bit into it letting the clutch out too heavy at a uphill light on a over weight container at 104K pounds gross.

And you wonder why I have issues with rigs who deliberately design failure a shaft to protect the entire drive train from a more costly failure. It's a failure on a larger scale.

 

If you're not familiar with rear ends,I'd take it to someone that is, it could be as simple as a snapped axle, the difference lock obviously works or you wouldn't have made it home, I'm guessing you don't have a positive lock, so the first thing I'd do is pull both axles out to check the shaft and spines.

 

Likely a damaged through shaft in the forward drive. Could also be a damaged or broken axle shaft in the front drive. Have seen the front drive crown and pinion gears strip off as well. Won't know what has failed until you start taking it apart. All you know at this point in time is the issue is in the forward drive axle.

 

Can't be a bad axle. The jack shaft going to the rear rear end isn't even spinning so that eliminates that .
And if he had a axle broken in the front rear the he wouldn't of went anywhere.

It's in the power divider. Thru shaft is snapped. Probley from a shock load one time or another....

 

Broken axle shaft in the forward drive axle would give the same symptom the OP described. Power will always take the path of least resistance (which would be the snapped shaft if that is the failure, not saying it is). By locking in the power divider you would be locking the through shaft directly to the propeller shaft from the transmission. Power will be transfered straight through to the rearmost drive axle, which would be the only axle providing drive at that point. Like I said in my first post, there are multiple things that can give that symptom and the only way you'll know what has failed is to have it taken apart.

 

Mmmmmm
You don't quite understand how that system works .
Let me explain it or try to make you understand.
When the interlock is not locked power can be transfered to any 1 of the 4 wheels .
You have 3 differentials working together.each axle has its own differential and the power divider is another differential that splits the power to both front and rear diffs
With the interlock locked you have 1 wheel on each axle transmitting power.

This is why his axles are fine.

 

one way or another you have to pull the axle shafts out to pull front rear. so you will eventually find what broke.