what are the most common failure points of this axle? we got 20" of snow and while driving out of my snowed in parking spot i had 4X4, shortly after getting out the truck became hard to drive forward and i saw my front tires were not moving, just the back pushing forward. after a bit of rocking i got the trucks tires moving and now i have only rear wheel drive. there is no noise coming from the front axle while moving that i can hear, my Tcase is good as i cant move the front shaft while in 4X4. the front pinion feels to free spin but its hard to tell, i cant feel or hear any gear lash when spinning the drive shaft but this may be hard to feel in a 300K mile truck? i wont be able to pull it apart till Monday but i find it hard to believe i sheered a pinion with a factory truck and open diff... i figured the cad system would be the most common failure point but i wanted to know what you guys have experienced.

 

Check the CAD to make sure its engaging first. That is by far the most common reason 4WD doesn't engage the front axle. Check the vacuum lines going to the CAD.

 

all bypassed, it has a constant vaccume suction at the cad to engage it. its possible its broken but i wotn be able to check untill monday. way to much snow to get under the truck and nothing is plowed yet. 25" and counting over just a couple days. stuck using my half way assembled 2500 now.

 

I would guess the CAD is the problem. Even if you added a constant vacuum line it could be the diaphragm on the axle is frozen. You can remove the cad housing (4 bolts) to verify the fork position.
To keep this from being a constant issue you should get the posi lock.

 

ive had those posi before, ill just replace the shaft with a solid one. if the shafts are good but the collar is broke then ill pick up a collar but if the shafts are in any way shot im going solid, i have a 35 spline YG solid on my 2500 wtih a elocker eaton and ive never had an issue with it @ nearly 1500ft/lbs of torque. i cant imagine the dam split shaft cad crap saves but 1/4mpg at most? i mean its an open diff to start wtih so whats it rotating? one extra shaft @ maybe 10lbs and a 17in/lbs rotating carrier? seems like way to much added failure modes for such a small mpg impact...

anyway its a lake out there with the snow melting so idk when ill get around to pulling that thing appart, ill take picks when i do tho, see how bad the damage is