iirc, nothing holds the shaft in on the pumpkin side. there should be two wheel bearings, either 1 or two retaining nuts, and two c clips that hold everything together in a hub assembly. for all that to go bad to the extent that it did is almost impossible, but apparently it happens

 

I'm tearing into it tonight to find the answer, but Im assuming the C clip talked about must somehow be the answer as the axle came out of the shaft. Having not had this apart before I cant visualize what it looks like on the hub assembly but there must be a "spindle" that the axle travels through and that is the nut that backed off? Still dont get it. WIll let you all know.

 

hope your spindle is ok. if not some welding shops can replace it but its not cheap. the hub assy is held on by a single nut that has nylon on the outer 1/4 of the nut. then a wedged shaped think called a keeper is aligned with the key way on the spindle and pounded into the nylon to keep the nut from moving. i hope everything is ok and the nut just backed off.

 

there are no C clips on a full floating rear axle.

 

i didnt mean c clip, i meant snap ring. my rear hubs use a snap ring on each side

 

my guess would be bearing failure that caused the hub to come over the nut or the nut to back off,If you can get them I would look into stemco pro-torque nuts as repalcements for your axle,I have changed them on all my big trucks and the first time I pull the hubs off my truck I will be swapping them on,they use a snap ring inside the nut to lock it in place instead of the nylon and wedge

 

i have had this to happen many years ago. bearings is the only thing it can be. they are a little clip that sticks in the key way that keeps the nut from backing up. i would say that key came out and let the bearings get loose and they tore up and out comes the axle wheel and drum. this will make you think the next time you are running a 100 mph.